this topic was inspired from here http://slinging.org/forum/YaBB.pl?num=1499008756/new

at the pisture below you can see how i understand slinging.
please focus more on the principles of the way of acceleration than on other details. it still needs a lot of refining. 

http://slinging.org/forum/YaBB.pl?num=1280933160/15
here Aussie (reply #16)
talks about trail angle. read it.....


the picture explains how you can't compare slinging to circular motion with radius of sling(or hand + sling). it's more dependent on hand path and style/technique

Quote:

in the case of an object that moves along a circular path with a changing speed, the acceleration of the body may be decomposed into a perpendicular component that changes the direction of motion (the centripetal acceleration), and a parallel, or tangential component, that changes the speed.

tangential component is what makes the throw more powerful...

if you don't understand the forces applied read here: https://en.wikipedia.org/wiki/Circular_motion,
https://en.wikipedia.org/wiki/Centripetal_force
or learn more about mechanics in the web.

pirouette styles opperate on the same principles(ellipse might be closer to circle).
i believe that linear style are more efficient than pirouette but pirouette has more energy capacity thus pirouette might result on faster/ more powerful throws.

put in here your ideas on how high velocities are achieved and what  can be done to achieve even more speed/ power

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I think there is a element of body movement. I think this is the extension that apex talked about . If you move forward when the pouch is behind you its adding force whether or not it's pirouette or a Byzantine. This then timed with the trail Aussie talks about and a good technique.

I want to look further into this later on when I have time but essentially, I still think that a circular motion model can approximate the tension through the arm and sling at point of release (with the inclusion of the arm of course).

No matter what complex combination of circles/ellipses leads to the throw, at the exact point of release it still appears that the projectile travels (roughly) perpendicular to the radius and the leading angle becomes small or 0.

Regardless of the wind up, at this small time interval around release the system is pretty much circular motion so:

F=(mv^2) / r

Should still apply at point of release.

The physics around the wind up and whether a sling of x size can actually be accelerated to that speed with air resistance etc seem to be a lot more complicated though.

For example to create some elliptical motion, may actually require more tension than circular motion at the point of release, but this wouldn't necessarily mean a faster moving projectile, just that the direction of the projectile is pulling more against your arm. Hope this makes some sense...

The whole thing is quite interesting so I might try devote some time to trying to hash out some physics to the whole thing. I've not really looked into elliptical motion before especially with considerations such as air resistance. So might be able to work some stuff out.

JudoP wrote on Aug 16^th, 2017 at 7:46am:

The whole thing is quite interesting so I might try devote some time to trying to hash out some physics to the whole thing. I've not really looked into elliptical motion before especially with considerations such as air resistance. So might be able to work some stuff out.

Take for this once more a very "exactly" look at this video: https://www.youtube.com/watch?v=rzUAdkoAfbo - especially at the extreme slow motion of its first throw.

There happens something "crazy", because right before release (respectivley in the beginning of the last half rouund) the arm and hand already moves forward in a time, where the pouch still moves in counter direktion (means "back").

in the graph above i have made the assumption that the tension of the sling is constant through out the throw, but in fact that won't be the case.

in reality i think it's more difficult to apply big forces at the end (extended arm) of the throw than at the beginning, so the blue force vector (tension of sling) will start big and become smaller while throwing.

the more ellipsoid the throwing motion is:
[list bull-blackball]

the faster your hand needs to be,the more difficult it is to apply force(accelerate)
remember that the slingstone is going to travel faster than your hand most of the time during the throw

the easier it becomes for the arm to withstand the otherwise huge forces caused by small radius of curvature(of a more circular motion)


@JudoP i might be repeating myself here...
the law of physics you used (F=(mv^2) / r) applies to any motion of a body that changes direction (centrifugal acceleration).
You just used the wrong radius.
only in circular motion the radius of the circle equals the radius of curvature, here we don't have circular motion...

you could make make a rough example out of the above graph to understand the difference.

if above is in scale 1:20
then the sling is 80cm(=20*4cm)
let's say the slinger threw 100g stone 50m/s
1)doing it the wrong way and instead of radius of curvature we put the length of the sling 0.8m then F=312.5N
2) the right way would be : radius of curvature=(20*12cm)=2.4m
F=104.1N much less...

this also shows how bad use of long slings loses to good use of short slings

@Mersa the extension (Apex-apoc talks) comes from the combined movement of arm and body but is measured by the initial and last position of the arm

Apex-apoc's model has a multiplication  i don't understand and isn't explained

@Apex-apoc feel free to add your drawings and tables in this thread too.

johan wrote on Aug 16^th, 2017 at 12:33pm:

@Apex-apoc feel free to add your drawings and tables in this thread too.

Yes, thanks: My idea is to draw 24 circles in a linear row of 24 steps of (linear) "extension". On each circle the pouch (respektivley sling line) shows an other "time" - thats like the "second hand" on a watch (while moving the watch linear at the same time).

Each position of pouch than is a "red point" on his own circle (dial). If all red pointes will be connected through red lines, all red lines in this row of circles would build up a quarter of an ellipse (or something what is only similar to an ellipse). If this is done then also should be insert the parallelograms of vectors (force or velocity).

The distances between all circles of this row, of course had to increase from step to step (frame to frame) for showing the accerleration of the circle (while extension).

If this will explain and / or benefits something I hope than to see.

But I have already now the suspicion, that the flater "streched" parts of elliptical curve are longer and its lenght will be a measure for velocity (or force of acceleration) - similar to vectors.

So it would be nearly the same result as it is allready shown with my first drawing. But we will see ... perhaps!

johan wrote on Aug 16^th, 2017 at 6:51am:

put in here your ideas on how high velocities are achieved and what  can be done to achieve even more speed/ power

Three things in your drawing (in future we will need numbers for each new drawing) I do not understand:

1. Why is the "Sling = 4 cm" ?
2. Why is the path of hand a curve? (for extension I pull my hand from behind of me straight on / linear in direction of target).
3. Why is the "R" 12 cm only

Is your drawing not modelling a whole sling (which has more like 90 cm than only 4 or 12 cm)?

I mean is this a "scaled" drawing or is drawn here a minimal move of a hand only?

Scaled has this to be in anyway (because the screen is so small), but to scale "amounts" too is a little bit confusing. Thats like the remark "26,7 cm" to name the distance  between London and Berlin at a map.

I mean, what in reality is "100 cm" has also to be described as "100 cm" - regardless the scale.

@ Apex apoc
i think that i've already talked about that.

johan wrote on Aug 16^th, 2017 at 6:51am:

please focus more on the principles of the way of acceleration than on other details. it still needs a lot of refining.

the drawing talks about how acceleration happens.
it's just an example...
but if want to put values to understand better as i did above (reply #4) then use whatever ratio you want, it won't change the general analogies. (i think this answers questions 1 and 3)


you can't find velocity from the above graph it's too generalised

2) i thought too that the arm goes straight but then i watched closely to some videos and made that conclusion. some people or styles may do it to greater extent than others.
is it good for speed? i don't know .
making better graphs or modeling real life powerful slingers vs noobs can answer some questions...

johan wrote on Aug 17^th, 2017 at 3:19am:

2) i thought too that the arm goes straight but then i watched closely to some videos and made that conclusion. some people or styles may do it to greater extent than others.is it good for speed? i don't know .

You are right - my false: While doing the "extension" the hand turns necessarily around the joint of elbow (and shoulder). It does only "feel" like a linear move but is a (flat) curve.

Good to know!

Quote:

@JudoP i might be repeating myself here... the law of physics you used (F=(mv^2) / r) applies to any motion of a body that changes direction (centrifugal acceleration). You just used the wrong radius. only in circular motion the radius of the circle equals the radius of curvature, here we don't have circular motion...

I think you may have missed one or more of my posts from the other thread.

The consideration of adding the arm into the radius was a simple error which I've rectified (more accurately the center of rotation might be the center of the torso rather than the shoulder).

I take your point that the motion is elliptical and not circular- my suggestion is that circular motion would probably approximate the behavior of the system at point of release.

If you consider circular motion vs elliptical the difference is that the velocity of the projectile is perpendicular to the direction of the radius at all times, whilst in elliptical it varies to tighter and wider depending on position in the curve (caused by varying centripetal force).

At the point of release on your diagram the velocity is more or less directly perpendicular to the radius to the center of rotation which means the motion is essentially identical to circular over this range (or at least a good approximation).

This should be true even with more complex behavior beforehand.

I'm not proposing a full mathematical treatment of the system here, only a relation that *may* hold accurate at the point of release only.

Another consideration is that the arm might not be fully straight at release, in this case the radius could be reduced and you could calculate the torque on extending the arm.

analysed some vids of me, see the pictures below.
fig8 modified and underhand

pictures are 2dimensions and it may confuse you because if the sling is canted to the picture, sling will appear shorter...

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johan wrote on Aug 17^th, 2017 at 4:39am:

fig8 modified and underhand

Also this picture (from Wikipedia / Onno) may be help to imagine where does extra accellerations come from (while slinging the last half round). Special here (mechanical "overhand style"): The path of "hand" while "extension" is a circle (respectively an orbit) too. Here the ellipse results from superposition of a circular move to another circular move. But I think this resulted path isn't really (called) an "ellipse", but a "klothoide" or "hypercyclus" ... or neither nor.

And still I think, the "extra accelaration" would be as higher as smaler the ellipse is (means: ... as higher the relation of smaler and larger axis is). So it would be better to hold the extension-path of slinging-hand as flat as possible.

---

Great diagrams guys

I do not know much about math. I'm just throwing sling.  :D

(But I was wondering if I would make a tutorial throwing of pirouette.)

I've wondered a lot about this before.

Unfortunately, I don't have a camera that has enough fps to see my throws all that well. Even on my phone's "slow motion" setting (which is ~240 fps, but not really because of the way the shutter works), my arm moves too quickly to see the details of the throw -- even when I'm tossing pretty slowly.

Personally, I don't think that near the release the motion is super circular. This depends on your technique, but for fig-8 at least, it's much more elliptical during than circular. For something like apache, the motion is pretty circular.

I think if you are looking for the math, it's easier to figure it out for apache than most other styles due to the nearly circular motion. Part of the issue is that the sling does not extend straight out from your hand until the very end of the throw.

It is clear that the extra force comes from the extension of your arm by the sling, but beyond that, I'm not sure how to calculate it. I think it's very dependent on the slinger and their technique.

I have a slow motion Apache throw in my intro http://slinging.org/forum/yabbfiles/Attachments/trim_A9A8F9AA-D5A8-4E83-8B40-CFF5008FB69A.MOV

Pouch lag is pretty evident and motion more or less circular.

cpman wrote on Aug 18^th, 2017 at 5:50pm:

I think if you are looking for the math, it's easier to figure it out for apache than most other styles due to the nearly circular motion. Part of the issue is that the sling does not extend straight out from your hand until the very end of the throw.

But the origin idea was to get the "math" of that kind of slinging style (helicopter / side-arm) that could achieve ranges far more than 300 m.

Apache style is like a simple circular slinging without "extension", because to rotate an streched arm over head is not much more than a simple circular slinging.

To sling a stone with slings of length 1,00 - 1,40 m and up to 3 rounds per second achieves stone-velocity of maximum 30 m/s. But to achieve far more than 300 m we need velocity(s) of 60 - 80 m/s. So we need to study a slinging style that is able to multply the "initial velocity" of 25 - 30 m/s.

I mean we do not searching for the math of a simple "carousel" or salad spinner, but the math and conditions for multiplication of its velocity. 25 - 30 m/s has to become 60 - 80 m/s.

For this "secret" to study (and to solve) we need more stuff like this: https://www.youtube.com/watch?v=AwuJae3aRe0 (filmed from over the slingers head)

I am convinced with the "fact" (better: "idea") that the searched / hidden "factor" comes from the relation of small and large axis of an (far) extended circle (= like an ellipse).

That's not exactly the same as the princip (super circle) of that "trebuchet" that I posted the day before yesterday.

_____________________________________________________________________________

Remarked just by the way: The long english terms "the day before yesterday" and "the day before the day before yesterday" sounds in german simply "vorgestern" und "vor-vor-gestern" (... thanks god!).

I should point out that apache still causes an elliptical path like the diagram of the trebuchet. It has a lead angle which decreases to zero on launch. Effectively causing elliptical motion.

I've been looking at the more complex styles a bit (and practicing them a bit to try and understand the feel). It's unclear to me whether there is any real qualitative difference between them and the basic styles, or whether they work by a similar, but different mechanism. I'm just going to try and mathematically 'get' the simple sort of trebuchet-sling movement then perhaps I might be able to work some stuff out about the others  :D

The distinction from what I can figure out is that the drive from the hand in these other techniques is pretty much directly forwards with a very large trailing angle which then quickly whips round, it's this drive which is the limiting factor of the throw essentially. Compared to maybe a basic apache movement which is working on a circular rotation of the arm.

What might be the key thing to work out is the force of the explosive drive or the torque on the limbs required to cause the acceleration of the projectile (this might be very difficult to get realistic figures on). I suspect that the centripetal force causing tension on the arm (F=mv^2/r approximately..) becomes relevant for very heavy stones where even a moderate speed rotation will apply a lot of force pulling the arm straight. For fig 8 ect this can ruin your kinetic chain and stop you putting a lot of drive into the throw (just try throw fig 8 or sidearm with a v heavy stone to see what I mean, it'll drag your arm straight and effectively make it a poor mans apache style).

JudoP wrote on Aug 19^th, 2017 at 1:34pm:

I should point out that apache still causes an elliptical path like the diagram of the trebuchet.

... but only when the sling is shorter than the arm (50 - 70 cm) ... as it is at the shown trebuchet.

When the sling is much longer than a slingers arm (90 - 140 cm) then the difference between small & large axis is so small (much less than 50 %) that the ellipse is very similar to a simple circle. 

And when the sling were right twice as long as the arm, than the trebuchet couldn't work at all anymore.


What do you mean with "lead angle"? Is this the angle at or in the arm of trebuchet (so "zero" while release)?

johan wrote on Aug 17^th, 2017 at 3:19am:

2) i thought too that the arm goes straight but then i watched closely to some videos and made that conclusion. some people or styles may do it to greater extent than others.is it good for speed? i don't know .

I have to change my opinion on this again, because the "deklination" of the hand to describe a curve is not much more than the "deklination" to wind up the simple slinging-circle.

I mean the hand goes around in a circular curve (to drive the bullet) all the time of slinging. So this "curvy path" also has to be ignored in the move for the last half round (right before release). In other words: "Show the hands path and motion allways or never!"

It's not so important (to show) where the hand goes, but where the circle goes, and right this goes pretty stright on (a linear path) in direction of target.

I've also been throwing different styles to try decipher the code.
I agree with judop about heavy stones in certain styles.
Experienced it first hand.


Do We want a degree of trail angle or pouch lag???

Happy to try film stuff if anything is needed

Mersa wrote on Aug 19^th, 2017 at 6:52pm:

Do We want a degree of trail angle or pouch lag???

i think that pouch lag creates acceleration or otherwise put , it is a position of leverage/power position.
it doesn't seem to tell us a lot about final speed.

below is a picture of mod fig8 with higher speed than the last one. sorry for the quality it was filmed from far away.

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Apex-apoc wrote on Aug 19^th, 2017 at 2:12pm:

JudoP wrote on Aug 19th, 2017 at 1:34pm: I should point out that apache still causes an elliptical path like the diagram of the trebuchet. ... but only when the sling is shorter than the arm (50 - 70 cm) ... as it is at the shown trebuchet. When the sling is much longer than a slingers arm (90 - 140 cm) then the difference between small & large axis is so small (much less than 50 %) that the ellipse is very similar to a simple circle.  And when the sling were right twice as long as the arm, than the trebuchet couldn't work at all anymore. What do you mean with "lead angle"? Is this the angle at or in the arm of trebuchet (so "zero" while release)?

There would still be pouch lag with most any sling you could actually do apache style with, I've thrown apache with my approx 90cm sling before and it's definitely not just a straight extension to the arm. It may be less so with longer slings but I think you would struggle throwing apache at all before it gets too long.

Lead angle- Ah yeah sorry, this is established forum lingo. Essentially this is a measure of the pouch lag, it's the angle of how much the sling is behind a radial path (if that makes sense).

JudoP wrote on Aug 20^th, 2017 at 4:40am:

Lead angle- Ah yeah sorry, this is established forum lingo. Essentially this is a measure of the pouch lag, it's the angle of how much the sling is behind a radial path

So this one, perhaps? (... "36,6°" for example only) ...

... or the other one underneath? (... "28,91°" for example only)

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So the 36.6 degrees I think, assuming the red line is the arm.

JudoP wrote on Aug 20^th, 2017 at 8:42am:

assuming the red line is the arm.

Ähm ... not really. The arm isn't drawn here, but the red line nevertheless is the radius of the hands motion-circle. But the middelpoint of this circle is neither the schoulder nor the ellbow and therefore the red line can not be the arm, although similar to this.

Let's say it's the "forearm" (at the most).

johan wrote on Aug 16^th, 2017 at 6:51am:

put in here your ideas on how high velocities are achieved and what  can be done to achieve even more speed/ power

I think I have solved the "enigma" of a moved slinging-circels "extra power", because in replacement of "classical physik" with "modern physik" Einstein said somthing like: "There is no difference between heavy mass and sluggish mass".

That means it doesn't matter if a body is in a field of gravity or in a other caused (= forced) acceleration - in both cases the body will experience a force that moves it. So try to imagine the "stone" were not in a sling but in a pendulum or a weight at the edge of a "turn table" (germ.: "Plattenspieler").

When it is a mass on edge of a turntabel and you move the whole turntable happens the same as happens when it is a pendulum in a field of gravity: The mass (bullet) moves (accelerated) to the deepest (respectivley "southest") point.

The same happens when the system is a moved slinging-circle (is in principal the same as a turntable), but in a slinging-circle there also is an initial velocity (while the turntable stands still).

That means the mass or bullet in a slinging-circle gets an acceleration and its velocity does increase. But this were only the first step of increasing the velocity, because in a second step it gets the velocity from moving it to the "northest point" .

Let's say, the bullet has had the initial-velocity of 22 m/s (= 3 rps):

Cause of moving the slinging-circle with 10, 12, 15 ... up to 25 m/s this velocity increases from 3 rps to 4,5 rps (for example) - allready achieved in the "southest point" (or "position). From there these 4,5 rps gets another acceleration by addition of that velocity what is the hands velocity while fullfilling the "extension" up to the point of release: Perhaps another 1,5 "rps" once more.

In the total sum that makes 6 rps what is somthing like a doubling of the initial velocity. In this case the "factor" would be "2,0" (... 2 x 3 rps = 6 rps = 44 m/s). How this principally works (in the first stage) shows my drwwing (Image P-01).



Note: For throwing a (base-) ball by pure hand mens hand can be acclelerated up to 46 m/s within a very short time (unfortunatly I do not know the shortest time exactly but I guess somting about a tenth of a second, so perhaps within 1/10 or even 1/15 sec.). While starting such a throw hands speed of course is not so high as in ending the throw with then achieved "top-speed": In its first tenth second the speed achieves probably up to 5-10 m/s only.
But in opposite (or: ... in contrast) to the baseballplayer (pitcher) the slinger has the advantage that his balls mass doesn't drag against hands move: When a slinger starts the "extension" (thats compareable with a baseballers start of throwing) the ball is passing the "west-point" of its slinging circle, where it practically causes no resistance against hands work. That is similar to throwing a ball without weight or mass. Therefore in the beginning the slingers hand can reach even more velocity as a baseballers hand (perhaps up to 15 % faster). 
First when the slingers ball reach the sling-circles south-point (respectivly the southern zone of the slinging-circle) the ball began to drag against hands move.



... and now I will draw this special kind of moving in 24 "steps" (means as much as "frames") to show what happens in one half of a round (what is 1/6 second only). extensionextensionextension

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Apex-apoc wrote on Aug 20^th, 2017 at 9:42am:

JudoP wrote on Aug 20th, 2017 at 8:42am: assuming the red line is the arm. Ähm ... not really. The arm isn't drawn here, but the red line nevertheless is the radius of the hands motion-circle. But the middelpoint of this circle is neither the schoulder nor the ellbow and therefore the red line can not be the arm, although similar to this. Let's say it's the "forearm" (at the most).

I'm not really sure where it fits in your model exactly then. Maybe the 28 degrees figure is more useful for non-simple arm positions, as the 36 seems to be referencing something a little abstract.

If you look at the trebuchet diagram on page 1 the lead angle would be the (acute) angle between the solid arm and the line of the sling part.

timpa wrote on Aug 17^th, 2017 at 12:36pm:

(But I was wondering if I would make a tutorial throwing of pirouette.)

I would love a pirouette tutorial. I'm trying to get good with long slings but I can only match the range of my 30-35'' ones.

I'm far too nervous to use pirouette. I just hate the idea of throwing in the completely wrong direction. With all other styles I can basically send it out the way my body is facing. Spinning around... I would really have to be in an empty field with no-one and nothing around me for at least 400m.

Pirouette seems worse than it is.

Remember "Image P-01"  http://slinging.org/forum/YaBB.pl?num=1502880716/15#26

My next drawing (Image P-02) is partially the same Image and shows the same situation but explains how the new path-position of the bullet has been "constructed". While studying the draw you will understand why I have to do this semi-step. If I would draw  all "explantions" in the same drawing it would be to understand no more.

For further explanations let's say the bullet gets thrown right to the north because to bring the balls progress in some words some positions on the sling-circle have to have special names.

So in the last half round right before release the bullet comes from the north, runs through the position "west" (where the "extension" and "extra-acceleration" starts) to the south (southern point), and from the south to the east-point where it get a right "northern" flight-direction" again.

Where I wrote "Sling-direction: Counterclockwise (right-handed - target right in the north" there I ment "... right in northern direction" of course.

Note: In this drawing it looks like the ball would become slower (falling back) but taking this for real would be a fallacy only. Indeed the same bullet right in this position had became faster (32 m/s), although relativ to the hand only. Right this is THE (solved) MIRACEL !     THINK TWICE ! ! !


In a third drawing ("Image P-03" ... coming soon) I will explain and draw how the velocity and ball-positions are to construct, if the acceleration happens right between "east" and "south", because this also is some "tricky".

---

Are you just adding the speed of the hand to the speed of the ball from rotation?

I'm pretty sure that won't work. The sling cannot be separated 'physics wise' from the hand motion in calculation- they effect each other.

Your throwing motion provides centripetal (inwards) force which transfers linear force to a circular acceleration.

JudoP wrote on Aug 27^th, 2017 at 6:51am:

I'm pretty sure that won't work.

That works! If your accelerated hand hits against a ball that is allready accelerated in counter direction, than this hurts your hand much more as it would be when your hand (or the ball) stands RELATIVE(LY) still. For computing the eneregy of "crash" hands velocity and balls velocity have to be sum up! Thats your: "... effecting each other".

Please read my explanations for Image P-01 (!) - "there is no difference between heavy mass and sluggish mass" (imagine a pendulum in a accelerated space-ship - it would swing even without gravity ... because "gravity" is nothing else than acceleration ... said A. Einstein ... and therefore I said: "... THINK TWICE ! ! !")!

Also note: Even if you stand still on / at earth your velocity is not "sero" but the velocity of earth surrounding the sun plus the velocity of sun surrounding milky ways "center" plus the velocity of this center crossing the universe ... because VELOCITY IS RELATIVE ! ! !

So you think you would be standing still or could achieve velocity of 0,00 m/s, but right this thought is WRONG. ... Never and nowhere you can achieve "sero velocity". Your velocity is allways and all over the universe the velocity of your atoms, respectivley its "particles"!

Also note: In this "construction of slingers hidden dynamic or acceleration" we have to achieve a velocity that is MUCH MORE than "initial velocity" (that is maximum 30 m/s = 108 km/h)! How should this be done if not while solving that "miracel physic" that most people dont know or understand?

We need to construct more than 240 km/h (67 m/s) velocity of already slung stones, because these stones velocity has been thrown and measured already for real! But this speed is absolutely not to achieve while spining up a sling in a simple circle. This large difference in amounts of velocity have to come out of "circles fast acceleration" (here called: "extension").

And I higly recomend to check this "theory" with that "marble in a can" that I have described allready!  That's a very cheap and simple experimental setup and easy to use (... if not having a can, than take a pot, a cover or a bucket instead of can, but in each case it should have a flat ground and a steep border ... and diameter about 15 cm).  ...

   


My next drawing (Image P-03) shows how the ball-position is to construct when the angle of balls moving-direction becomes different to the angle of hands moving-direction: 

---

Sorry - also in text of this Image I wrote a failure: "Position in Ball P0" is non-sense of course.

I will correct it and upload anew in a few hours.

EDIT: ... and another special problem here is not to know hands velocity, progress and accelaration exactly. This I can estimate only, but in the end of "extension" it should be something about 40 m/s (because baseball pitchers achieves something similar - but that can't totally taken for the research of slinging, because a by sling accelerated ball at least causes more "weight" than a baseball. In the first stage of acceleration a tough slingers hand becomes faster, but in the last stage it becomes slower than a pitchers hand. In the first stage a pitcher drags a baseball - 142 -148 gramms - but a slinger in the same stage has to drag nearly "nothing". All weight of the ball ... and more ... a slinger drags first when the ball is crossing the "south-point" of its slinging-circle! Also this is the slingers secret of a slingers advantage in throwing stones, balls or baseballs!).

Quote:

A close terrestrial analogy is provided by a tennis ball bouncing off the front of a moving train. Imagine standing on a train platform, and throwing a ball at 30 km/h toward a train approaching at 50 km/h. The driver of the train sees the ball approaching at 80 km/h and then departing at 80 km/h after the ball bounces elastically off the front of the train. Because of the train's motion, however, that departure is at 130 km/h relative to the train platform; the ball has added twice the train's velocity to its own.

source: https://en.wikipedia.org/wiki/Gravity_assist

very nice idea but it still needs a lot of thinking and explanation so we can transfer it to slinging.
gravity is much more different than human kinetics.

EDIT: now that i think more of it , it seems a very good explanation.
hmm.. i need to digest the idea.... :-/

I'm struggling to see where you are coming from on some points (possibly language- apologies I only speak English).

You seem to be putting out some confused ideas about Einstein's relativity which is not at all relevant to this problem. Relativity was a thing before Einstein. Specifically, the 'relativity' Einstein formulated is only really needed for near light speed objects or very high gravitational fields.

Ok- let me try to illustrate where I'm coming from.

I presume you would agree with me if I said-

1) I'm standing on a train going 15m/s.

2) I can throw a ball at 5m/s on flat ground, so...

3) When I throw it on the train it will fly at 20m/s relative to the ground (ignoring air resistance).

This is more or less where you are coming from correct?

Although the above holds true for trains and balls- it's based on assumptions, which means it's not a generalisable result much less a law that can be applied to other non-similar situations, like circular motion.

The most critical assumption is that you cannot generate comparable momentum to the train (or enough to dislodge your footing for example).

To illustrate the point:

A normal person throwing a tennis ball for example- it more or less holds.

A superhuman throwing a 100 ton train carraige at 300m/s?

Well... the model breaks down. For starters, anyone imparting the kind of force to generate that speed on such a heavy object would simultaneously propel themselves backwards with an equal momentum (which would translate to incredible speeds for human sized throwers). If they were somehow 'attached' to the train it would also drag the train backwards at high speed.

In other words the adding velocities like above works in certain situations with certain assumptions made.

That isn't to say that:

V(ball)=V(Hand) + V(ball relative to hand)

This is clearly true at all times, and about all things. However, this is a result purely dependent on viewpoint, it has no predictive power except the subjective experience of physics. You seem to be confusing this with a physical situation like my train example above.

--

I've finally gotten round to trying to figure this out properly, I haven't really got far except trying a ton of things.

From observation/experimentation- I'm starting to think that most of the force of the throw comes from the hand in direct opposition to the radial direction of the sling (you are driving in exactly opposite direction the line of the sling). This increases the centripetal force towards the center of rotation, therefore increasing angular velocity (this is probably more easily illustrated with a picture).

Unfortunately I think there's a bit more to it than that, the effect of the center of rotation moving etc. It's possible the factor of 'velocity adding' may have some role within a more complicated framework.

johan wrote on Aug 27^th, 2017 at 9:22am:

hmm.. i need to digest the idea....

Yes - and my head now is glewing light-orange-hot too and began to smoke like a comet diving in into earths atmosphere ... while thinking about "undigested rocks (& slings)".

But I think also it's no more very far until a viewable / understandable congruency with keplers second and / or third law. Right because gravity is (probably)* nothing else than "accelarity".

___________________________________________________________

* Albert Einstein said: "... probably ..." - that means even he wasn't absolutly sure in his new evaluation in masses "nature" (... weight and inertia).

JudoP wrote on Aug 27^th, 2017 at 10:44am:

From observation/experimentation- I'm starting to think that most of the force of the throw comes from the hand in direct opposition to the radial direction of the sling (you are driving in exactly opposite direction the line of the sling). This increases the centripetal force towards the center of rotation, therefore increasing angular velocity (this is probably more easily illustrated with a picture).

Sorry, but this is right that what I have drawn and explained: Can't you see the directions that I have drawn for hand and ball ???  These directions stands "in exactly opposite direction the line of the sling" in my drawing too, and all the time I was talking about this.


JudoP wrote on Aug 27^th, 2017 at 10:44am:

... increasing angular velocity (this is probably more easily illustrated with a picture)

Yes - but a picture stays a picture. What number or kind of pictures (or illustrations) do you still need??? 

I think about Einsteins "realativity" you are thinking to much "exotic". His relativity isn't no other than a absolutly common relativity as is called also "proportion" or "relation (-ship)" ... for example. 

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Sorry, but this is right that what I have drawn and explained: Can't you see the directions that I have drawn for hand and ball???

It's not the same, as far as I can tell.

You are depicting a the hand with a forwards velocity, no force depicted (note that the curved circular path leading up to the throw implies a radially inward force).

What I'm saying is that (I suspect) that the majority of the sling release speed is generated from a force directed radially inward which increases the angular velocity. Of course- where 'radially inward' is depends somewhat on the lag angle of the sling. I'll do some drawings later and see if I can explain it better.




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I think about Einsteins "realativity" you are thinking to much "exotic". His relativity isn't no other than a absolutly common relativity as is called also "proportion" or "relation (-ship)" ... for example.

No, it's totally different. Einstein's relativity is exotic and turns traditional notions of frame of reference on their head.

Different reference frames and the idea of 'relativity' have been around as long as mechanics. Since Newton at least.

JudoP wrote on Aug 27^th, 2017 at 11:27am:

It's not the same, as far as I can tell.

Than you are reading my drawings wrong. I drew and wrote: "Hand wents to the NORTH and ball runs to the SOUTH (resp.: "southern point")".

And note: Moving direction allways only can be the force(s) direction, because where is no force there also is no move - movements and forces has allways the same direction (resp.: "force" is and has no direction at all - that are "amounts" only!).

Apex-apoc wrote on Aug 27^th, 2017 at 11:51am:

And note: Moving direction allways only can be the force(s) direction, because where is no force there also is no move - movements and forces has allways the same direction (resp.: "force" is and has no direction at all - that are "amounts" only!).

completely wrong idea if there is initial velocity.

Apex-apoc wrote on Aug 27^th, 2017 at 11:51am:

JudoP wrote on Aug 27th, 2017 at 11:27am: It's not the same, as far as I can tell. Than you are reading my drawings wrong. I drew and wrote: "Hand wents to the NORTH and ball runs to the SOUTH (resp.: "southern point")".

I don't see any point on your diagram where the hand is moving in the exact opposite path to the ball. The ball might be rotating towards S, while the hand moves directly N. That is not what I mean. I mean directly opposite to line of sling.



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And note: Moving direction always only can be the force(s) direction, because where is no force there also is no move.

Common misconception-

The (sum of all) forces creates an acceleration or change in velocity, not a velocity- (by F=ma).

If I throw a stone up in the air the only force is downwards due to gravity, however the velocity is still upwards for a time.

Similar situation in standard circular motion-

The force (and acceleration) is always towards the center of rotation, yet the velocity is always tangential.

When a planet orbits there is no force pulling it sideways correct? Just gravity pulling it inwards.

JudoP wrote on Aug 27^th, 2017 at 12:06pm:

If I throw a stone up in the air the only force is downwards due to gravity, however the velocity is still upwards for a time.

Nonsens! If the only force were towards due to the gravity, the stone wouldn't be "thrown up to the air" but still lying on the floor - and in the other case the (falling) stone never would experience an air-resistance, "negativ accelertion" (= inertia or "delay") or a collision with the earth again from where it was taken.

On every body ever and allways works a force and its "anti-force" at the same time ... every action realize its RE-ACTION ... and if a slung stone gets a high "sounding" rotation from the conditions of release, then right because of this "anti-directions" from all graping forces. 

WHY satellites do not fall from heaven or leave the planet, if there were only ONE force ???

WHY heavy mountains do not sunk under ground ???

WHY should exist and to be accounted different "escape velocitys", if only that force counts, that made a body (mass) moving? "Moved once = moved for ever" ... or what ???

Apex-apoc wrote on Aug 27^th, 2017 at 3:00pm:

JudoP wrote on Aug 27th, 2017 at 12:06pm: If I throw a stone up in the air the only force is downwards due to gravity, however the velocity is still upwards for a time. Nonsens! If the only force were towards to the gravity, the stone wouldn't be "thrown up to the air" but still lie on the floor - and in the other case the stone never would experience an air-resistance, "negativ accelertion" (= inertia or "delay") or a collision with the earth again from where it was taken. On every body ever and allways works a force and its "anti-force" at the same time ... and if a slung stone gets a high "sounding" rotation, then right becaus of this "anti-directions" from all graping forces.

You're missing the point. There is an initial upwards force from my hand which accelerates the stone to an reasonable speed- me throwing it up, for example.

Whilst the stone is flying upwards there is only a downwards force on it (gravity). During the first half of it's journey it moves upwards despite the resultant force being downward.

Force causes acceleration, not velocity. Force and velocity can and often are in totally different directions- It's mechanics 101.

Talking about every action has an equal and opposite reaction doesn't explain anything- it just muddies the water.

JudoP wrote on Aug 27^th, 2017 at 3:28pm:

Talking about every action has an equal and opposite reaction doesn't explain anything- it just muddies the water.

No - the sling rotates because the pouch becomes a drag to the north on the one side of its circle, and a drag to the south on the other side of its (= same) circle. A circle (respectivley "twist" / tornado, ...) shows two antithetical "moments" at the same time and thing.

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WHY satellites do not fall from heaven, if there is only ONE force ???

Look up physics of orbits. Satellites do fall towards the center of the earth but because they are moving sideways fast enough so that they fall 'past' it.


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WHY heavy mountains do not sunk under ground ???

Well there is a reaction force from the earth in this case.


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WHY should exist and to be accounted different escape velocitys, if only that force counts, that made a body (mass) moving? "Moved once = moved for ever" ... or what ???

I don't see how it's relevant but-
Escape velocity only depends on the mass of what you are escaping from. It's the same for all objects on earth. It's essentially the speed with which an object moves such that it has enough kinetic energy to move away from a planet forever.

I'm not sure I understand the second part.

JudoP wrote on Aug 27^th, 2017 at 3:35pm:

Look up physics of orbits. Satellites do fall towards the center of the earth but because they are moving sideways fast enough so that they fall 'past' it.

Sure - but that are TWO forces at the same time and in counter-direction - not only one! So this example (and answer) speaks not for but against your own explanations!

Not I but you have to study this "physics of orbits" (respectively "physics all all") once more.

Apex-apoc wrote on Aug 27^th, 2017 at 3:39pm:

JudoP wrote on Aug 27th, 2017 at 3:35pm: Look up physics of orbits. Satellites do fall towards the center of the earth but because they are moving sideways fast enough so that they fall 'past' it. Sure - but that are TWO forces at the same time and in counter-direction - not only one!

I think you've misunderstood the equal and opposite reaction law.

There is only one force on the satellite, which is the inwards force towards the center of the planet. This force alone combined with the tangential velocity produces the circular motion.

The 'equal and opposite' in this situation is a force of the same strength acting on the earth(!) upwards towards the satellite.

It is an 'equal and opposite' force, however due to the huge mass of the earth it only imparts a very small acceleration.

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Not I but you have to study this "physics of orbits" (respectively "physics all all").

I'm sorry you've taken this personally. I have nothing in this but to get the physics right, which honestly may prove too difficult for my rusty skills. I won't hesitate to question things I know to be incorrect however.

For whatever it's worth- I actually have a degree in theoretical physics- believe it or not. Circular motion I first covered at A-level.

Even so, If you don't want to take my claims at face value wikipedia and google will be in agreement with them.

JudoP wrote on Aug 27^th, 2017 at 3:45pm:

This force alone combined with the tangential velocity produces the circular motion.

Wrong again, but also this and right the "combo" (... combined with what? "alone" ???) are still TWO ANTI-THETICAL FORCES: Centripedal ~ and centrifugal force.

You see: The same thing becomes not better (or changed) from telling twice and once more - with or without any "degree" or "wikipedia"!

And now stop this conversation please, because we turn (talk) in a circle only.

JudoP wrote on Aug 27^th, 2017 at 3:51pm:

I'm sorry you've taken this personally.

Of course I did, because allready the "physics" are a "persons physics" (no person without or out of physics). Speak against physics if you want to speak against me or my mind, ratio, logic or LOGOS  :cheers:.

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Wrong again, but also this and right the "combo" (... combined with what? "alone" ???) are still TWO ANTI-THETICAL FORCES: Centripedal ~ and centrifugal force. You see: The same thing becomes not better (or changed) from telling twice and once more - with or without any "degree" or "wikipedia"! And now stop this conversation please, because we turn (talk) in a circle only.

Obviously I still haven't managed to convey my ideas fully-

I'll leave you with this- centripetal is the only real force in the system. Centrifugal force is a 'pseudo-force' which is the result of using an accelerated reference frame (the ball, projectile- whichever, rather than a fixed reference frame).

I say it by no means as an insult- but you *can* learn all this on wikipedia etc. You stand no chance of understanding the motion of a sling without this understanding of how forces, accelerations and velocities work. Let alone the circular motion stuff.


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Of course I did, because allready the "physics" are a "persons physics" (no person out of physics). Speak against physics if you want to speak against me or my mind, ratio, logic or LOGOS  cheers.

Not sure what you are getting at here... Honestly though, I don't want this to be adversarial- I think if you can throw crazy distance then I would like to learn from you and improve my own distance throws, as you would have to have great technique to achieve such distances.

Just saying- from someone who has studied physics at a decently high level- (and wasn't half bad at mechanics)- your current theories of sling mechanics are not correct.

In addition, the fact you dispute some basic tenants of mechanics with me doesn't bode well for your prospects of producing a theory that actually works.

JudoP wrote on Aug 27^th, 2017 at 4:48pm:

Just saying- from someone who has studied physics at a decently high level- (and wasn't half bad at mechanics)- your current theories of sling mechanics are not correct.

Suuuper (*)! If instead your theorie is correct and from physics at its (decently) highest level, then you will much more easily and equal soon explain / declare where the "extra acceleration" of slung stones are coming from!

... but if not, then NOT!

So try to tell us (in mechanical details) the slings and human slingers generation of 240 km/h! And by the way: Lary Brays "stone" (!) had to be thrown with a "top speed" of 110 m/s - thats not only 240 km/h but 396 km/h ! ! !


_______________________________________________________
* In german we use to say "super!" instead of "perfect!" or "great!" if somthing is (super) great and / or (very) perfect!

Apex-apoc wrote on Aug 27^th, 2017 at 5:23pm:

JudoP wrote on Aug 27th, 2017 at 4:48pm: Just saying- from someone who has studied physics at a decently high level- (and wasn't half bad at mechanics)- your current theories of sling mechanics are not correct. Suuuper! If instead your theorie is correct and from physics at its highest level, then you will much more easily and equal soon explain / declare where the "extra acceleration" of slung stones are coming from! ... but if not, then NOT! Tell us (in mechanical details) the slings and human slingers generation of 240 km/h!

You don't have to have the full theory of how something works to reject incorrect theories- That is not how science works!

As I said before- I may or may not be able to develop a full explanation of this- but I will point out incorrect physics where I see it. It's better an open problem rather than one with an incorrect solution.

JudoP wrote on Aug 27^th, 2017 at 5:56pm:

I may or may not be able to develop a full explanation of this- but I will point out incorrect physics where I see it. It's better an open problem rather than one with an incorrect solution.

But thats also "nonsens", because if you not see a primitiv slings physics correct, so you can't make us believe to have seen my "mistakes" or any higher physics "correct" in the meaning of "completely". A "slings theorie" touches only physics basics ("grammar school") - nothing for "quantum physics".

So what should be a "problem" to you in explanations for a slings physics?

Do you allready miss (-understand) the "basics" only? 

Honestly I have to admit: The speech "I'm the degreeded specialist in math & physics but do not have to have (captured) the full theory of its basics" sounds a little bit "very crazy" to me - even right if you want to say not to know, where a simple stones high velocity of more than 300 km/h could coming from, but to know where I have done theoretical mistakes.

What corious kind of "degree" is that?

What means "centrifugal force is a pseudo force"? Do you know what is the so called "true and lonley force of a united theory (of all)"???

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But thats also "nonsens", because if you not see a primitiv slings physics correct, so you can't make us believe to have seen any "higher physics" correct. A "Slings theorie" touches only physics basics ("grammar school") - nothing for "quantum physics". So what should to be a "problem" in explanations for a slings physic? Do you allready miss (-understand) the "basics" only?

As you have glossed over my point:

Do you dispute that it is possible to reject theories whilst at the same time not proposing a theory of your own?

If you dispute this you are simply and obviously wrong, if not- then what I said is not nonsense, and my point stands.

---

You assume that the physics of a sling is easy?

You can't make that assumption when your theories of how it works are not consistent with/justified by the laws of physics. All that says is that you don't understand the physics. You've already made several statements that are just indisputably incorrect. Off the top of my head:

"The force is always in the same direction as the velocity."

"There are two forces required for circular motion to happen."

Then instead of acknowledging your error you just double down and try to mix in some other irrelevant concept that you don't appear to understand, like: Frames of reference, Einstein's relativity, Newtons 3rd Law (equal and opposite reaction) and centrifugal (pseudo)force.

Also, just because you can dip into mechanics late on in school it doesn't mean it's all easy. Mechanics can get extremely involved. I studied it alongside quantum mechanics and difficulty was similar.

I don't think you can really quantify larrys throw.
110 m/s is only one of the variables that contributed to the distance.
Spin of projectile Magnus effect and aero dynamics played a large role.
This could be argued on both the <110m/s>
We can speculate but we don't know the speed.

Maybe you can use this .
I know this isn't the internal ballistics but goes with my last post.

---

JudoP wrote on Aug 27^th, 2017 at 6:49pm:

Do you dispute that it is possible to reject theories whilst at the same time not proposing a theory of your own?

No - watching you I saw that it is not only possible but done actually. But "to be possible" doesn't mean "to be caused", "to be right" or "to be full of sense". The validity of a theory or a claim depends not on your jugdment - right not then if this judgment has no theory, causes or knowledge of its own - so to reject it only makes NO SENSE.



JudoP wrote on Aug 27^th, 2017 at 6:49pm:

You can't make that assumption when your theories of how it works are not consistent with/justified by the laws of physics.

Correct - but they ARE consistent with the laws of physics absolutely: Whilst the western hemisphere of earth runs to the east and the eastern hemisphere runs to the west the earth goes round and turns - one force and direction of move against the other while beeing TWO FORCES (and exacly how I had drawn!) - and when your claim is that the same thing were wrong or inconsistant with the laws of physics then much more your claim is indisputable incorrect. As you said allready: "It says that you don't understand the physics only."

Obviously you don't know only how to rotate a steering-wheel (with one hand or with two hands) or why it has to be fixed on an axis.

Fact is: The bullet at a moved slinging circle mostly is to compare with a rolling wheel, where the pouch is that point on the wheel that touches the ground and firstly stays "back on the road" while its axis go on. Right the point at its opposite moves with the highest speed (relative to the touching-point - not to the axis-point). Exactly this point then has to become the point of pouch (or bullet).

So what are we talking about, here??? About simply slung stones or about god and (his) whole world and physics?

Quote:

Honestly I have to admit: The speech "I'm the degreeded specialist in math & physics but do not have to have (captured) the full theory of its basics" sounds a little bit "very crazy" to me - even right if you want to say not to know, where a simple stones high velocity of more than 300 km/h could coming from, but to know where I have done theoretical mistakes. What corious kind of "degree" is that?

Well- physics is hard. What can I say? Especially when you bring in biomechanics. Even formulating the problem is difficult. You model the hand moving directly forwards- but In reality it appears the action is closer to an arc (and who's to say it's an 'even' arc, with even force throughout- it doesn't appear to be to me).

Even such simplifications are acceptable in coming closer to an accurate model, but you have to be meticulous in the mechanics to get anything remotely useful.

Adding a rotational velocity to a linear forwards motion just doesn't work like that. You have to think in terms of forces causing accelerations, which in turn change the current velocity. In moving your hand you are affecting the angular velocity because you are changing the force along the sling. Increasing such a force would likely speed up the rotation, which would make the higher speeds more achievable not less.

You claim it's merely 'high school physics' whilst getting 'high school physics' wrong in your explanation. Likely it's more like university level physics+, especially when you bring in the complexity of a human action.


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What means "centrifugal force is a pseudo force"? Do you know what is the so called "true and lonley force of a united theory (of all)"???

You're bringing in a grand unified theory now?? How is that even remotely linked? What do you want me to say?- Yes I've solved the foremost problem in physics and discovered the ultimate laws that govern the universe? To me this just looks like more obscurantism. It's not relevant to the discussion at all.

By pseudo-force, I mean It's not a 'real' force. It's a consequence of your own inertia or resistance to movement. Such 'forces' appear when you are in an accelerated (or non-inertial) reference frame.

This is the case if you are moving in a circle as there is a constant inwards force and therefore acceleration. Your speed remains the same but your velocity vector is constantly changing as you are moving in a curved path.

Mersa wrote on Aug 28^th, 2017 at 12:09am:

We can speculate but we don't know the speed.

What then do we know ??? That larrys stone would have had a spin that lifts his stone is speculated too.

But one is for sure: Energy for rotating the stone is a subtrahent to the energy for throwing a stone. Also a spinning stone is no "perpetuum mobile" for winning distance out of nothing.

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so to reject it only makes NO SENSE.

I'm sorry but that's not a justifiable position.

You can reject any number of unsupported, unevidenced or  logically inconsistent theories without replacing them with another theory.


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Correct - but they ARE consistent with the laws of physics absolutely:

As I have explained, they are not. Velocities do not just add like that.


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Whilst the western hemisphere of earth runs to the east and the eastern hemisphere runs to the west the earth goes round and turns - one force and direction of move against the other while beeing TWO FORCES (and exacly how I had drawn!) - and when your claim is that the same thing were wrong or inconsistant with the laws of physics then much more your claim is indisputable incorrect. As you said allready: "It says that you don't understand the physics only." Obviously you don't know only how to rotate a steering-wheel (with one hand or with two hands) or why it has to be fixed on an axis.

No idea what you are getting at here- you are really all over the place. There is no force rotating the earth, it has an initial rotation speed and doesn't slow down because there is no force effecting a (negative) acceleration.

I mean for every force there is an equal and opposite, that is true- but not in the way that you seem to understand it. There is just one force on the object in question- the other force is applied from the object to the effector.


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Fact is: The bullet at a moved slinging circle mostly is to compare with a rolling wheel, where the pouch is that point on the wheel that touches the ground and firstly stays "back on the road" while its axis go on. Right the point at its opposite moves with the highest speed (relative to the touching-point - not to the axis-point). Exactly this point then has to become the point of pouch (or bullet). So what are we talking about, here??? About simply slung stones or about god and (his) whole world and physics?

I've completely lost you. The bullet moves the same speed all round the circle unless you effect some force.

Mersa wrote on Aug 28^th, 2017 at 1:51am:

Maybe you can use this . I know this isn't the internal ballistics but goes with my last post.

I don't mean to lose this in an avalanche of posts. This is another layer of complication that could affect the result. It's an open problem as to how much or little the lift would effect the result. It could be nothing or it could be significant.

It's also a handy example of how not all mechanics is 'high school level'!  :D

JudoP wrote on Aug 28^th, 2017 at 5:29am:

You're bringing in a grand unified theory now??

No - this was done by you while claiming the difference between a "true" and a "pseudo force". When your claim is "xy is a pseudo force" than you have to explain what is the right or true force or the "force par excellance".

JudoP wrote on Aug 28^th, 2017 at 5:51am:

As I have explained, they are not. Velocities do not just add like that.

And I explained, they are (and how and why they are ... to add)!


JudoP wrote on Aug 28^th, 2017 at 5:51am:

No idea what you are getting at here - ...

Correct! To see comparabilities, "parables", connections and / or together hangs is not one of your talents.



My tip to you: Remember the topic and imagine a pendulum or turntable (what is as big as the earth, the orbit of our moon or as big as your slinging circle) as I have recommended while posting my first drawing (Image P-01).

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No - this was done by you while aiming the difference between a "true" and "pseudo force". When your claim is "xy is a pseudo force" than you have to explain what is the right or true force or the "force par excellance".

I have done so above. Again wikipedia is your friend here- the article on centrifugal force should set you straight on it's nature as a pseudo-force.


Apex-apoc wrote on Aug 28^th, 2017 at 6:00am:

JudoP wrote on Aug 28th, 2017 at 5:51am: As I have explained, they are not. Velocities do not just add like that. And I explained, they are!

No, you have insisted they are with no justification.

What force is applied by the hand? What acceleration does it cause in the projectile? Where is your free-body diagram showing this?

Physics is not guesswork and assertions. You need to actually justify your reasoning.


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JudoP wrote on Aug 28th, 2017 at 5:51am: No idea what you are getting at here - ... Correct! To see comparabilities, "parables", connections and / or together hangs is not one of your talents. My tip to you: Remember the topic and imagine a turntable (what is as big as the earth or as big as your slinging circle)!

That is not how physics works. You can't make a physical claim like "The velocities add" and justify it by bringing in all sorts of confused and irrelevant ideas from all over physics. Justify it directly through the laws of physics (mathematically ideally) or you are wrong. No matter what ideas you bring in.

It's not a matter of me not 'getting' your connections. I can see your 'connections' are confused rather than precise- I can see how the laws of physics contradict your assertions... and honestly it appears you are clinging on to whatever you can and bringing in whatever ideas you can, rather than accept your theory is not accurate. It's not a great attitude for developing a theory that works.

JudoP wrote on Aug 28^th, 2017 at 5:55am:

It's also a handy example of how not all mechanics is 'high school level'!

magnus effect is not in mechanics but in fluid dynamics(much more difficult)

johan wrote on Aug 28^th, 2017 at 7:17am:

JudoP wrote on Aug 28th, 2017 at 5:55am: It's also a handy example of how not all mechanics is 'high school level'! magnus effect is not in mechanics but in fluid dynamics(much more difficult)

The topics aren't so far apart. Fluid dynamics is part of fluid mechanics which is essentially a form of mechanics.

I wouldn't say it's way more difficult. Higher barrier to entry yes, you can't do it in high school.

https://en.wikipedia.org/wiki/Lagrangian_mechanics - This formed the basis of most of the 'pure' mechanics I studied in 3rd year, if you want an example of mechanics being equally complex with most other areas of physics.

no speculation on larrys stone spin. I've held it. It's more or less glande shaped. So you don't get sphere rotational lift.

As to the rest of the argument  - do either or you still know what you are arguing about ? :noidea:

It does seem to have resorted to simple name calling - albeit couched in physics terminology :-)

It's still clear to me  :(

Nonetheless you are probably correct that any more argumentation on this specific factor would simply be wasted time. I've made my points clear- anyone reading can check my claims with information on the internet and make their own judgement.

Either way, I wish no ill will. I just want to get the right answers and this compels me to post. As before I am still very happy to learn technique from Apex if he can sling as far as he claims- (and I have no reason to disbelieve him).

Now I'm going to enjoy bank holiday and do a bit of slinging  :)

JudoP wrote on Aug 28^th, 2017 at 6:29am:

No, you have insisted they are with no justification.

Aha!?? Please show or name us this post of mine (means: ... that post, where I wrote: "velocitys are without justification"). And then tell us the justified velocity of sun and / or earth (in a justified inertial-system or justified point of view)!

Or tell us instead of this, why only your point of view should be the "justified one": Turns the earth clockwise or counterclockwise ... watched from your point of viewing or "banking"?

In situations like this you can save a ton of time by doing a video first.

Isnt it possible to sling at a brick wall and use Audacity to get a rough estimate on release velocity? Even if its 30 meters away with tungsten there will be virtually no loss of velocity. Once you have a release speed that proves these numbers you guys can then focus on how its possible instead of whether it is or not.

I dont know much about the physics end but it seems like you guys can argue for another 10 pages and you wont convince each other.  :P

Quote:

Aha!?? Please show or name us this post of mine (means: ... that post, where I wrote: "velocitys are without justification"). And then tell us the justified velocity of sun and / or earth (in a justified inertial-system or justified point of view)! Or tell us instead of this, why only your point of view should be the "justified one": Turns the earth clockwise or counterclockwise ... watched from your point of viewing or "banking"?

Ok- I'll just summarise everything, though I fear I'm just repeating myself:

I've already said the route to a correct answer is analyzing the forces involved in a free body diagram and calculating the resulting accelerations. That's just your standard application of Newtons laws- it's how you solve basically any mechanics problem, my justification in saying this is that Newtons laws are correct(!)- (this is the part that you look down on as the 'easy grammar school physics' yet you have not managed to apply such physics, and have made claims in contradiction with such physics! eg: velocity always in the same direction as the force)

Just adding angular and linear velocities is not how mechanics works. It's an assertion that is unsupported. Have you considered how moving your hand changes the force of tension you apply along the sling- that alone means you can expect the angular velocity to change as you move into the throw. (Justification- by Newtons laws circular motion is directly caused by the centripetal inwards force (tension on the string towards your hand)- change the force or the direction of the force and you change the acceleration and therefore the angular velocity of the projectile).

The earth, the sun whatever else don't come into it and frankly I have no idea what you mean with those questions. The above point is the only question of relevance and needs to be addressed: How do you justify just adding the velocities?

I think I've said all I can say on this without rehashing. I've put the information out there and any more would just be going in circles or repeating myself.

I'm not sure if you believe I have a degree or not (can prove if not) but *please* consider that someone who has studied this stuff for years at a level well above high school (and who has actually taught high school physics for a time!) might know a bit more about it than a keen amateur. As I said before, I'm not doubting your claims and long distance throws, only your theory of how it happens. In fact if anything, theories involving the increase in angular velocity probably make higher projectile speeds more rather than less believable.

Honestly, I hope this is not felt too adversarial for you, I can see how my words could be read as such, but this forum is a nice space and I genuinely bear no ill will. Though I do value directness and getting things correct a lot in this realm (of physics).

If you can describe more of your throwing strategy to achieve high range I'd happily defer in that realm and be a keen student as my max range is probably no further than 200 or so meters, if that.

Morphy wrote on Aug 28^th, 2017 at 9:00am:

In situations like this you can save a ton of time by doing a video first. Isnt it possible to sling at a brick wall and use Audacity to get a rough estimate on release velocity? Even if its 30 meters away with tungsten there will be virtually no loss of velocity. Once you have a release speed that proves these numbers you guys can then focus on how its possible instead of whether it is or not. I dont know much about the physics end but it seems like you guys can argue for another 10 pages and you wont convince each other.  :P

This would be a valuable experiment to run for sure, but alas- the argument was already about how it's possible (or more generally how the sling produces speed) rather than whether or not it is  :-[

JudoP wrote on Aug 28^th, 2017 at 11:35am:

but alas- the argument was already about how it's possible (or more generally how the sling produces speed) rather than whether or not it is

... and right how it is possible I am in work to draw and have it partially drawn. But the same "mechanism" (or dynamic) is not only to construct in drawings but also to film AND FILMED ALREADY. So please don't care what JudoP's problem is here, because that what I am constructing here is proofed by experiments (made from "hard ware") already long: If a marble stands still in the "south point" of a can and you accelerate the whole can to the west (or to the east) very strong, then the marbel starts to run around along cans border "very fast" too. Normaly each child do experience and knowing this phenomenon by playing around with some similar "toys" ...

... EVEN THEN if JudoP want to ask me or himself still for long, what a can and a marble has to do with a bullet and a sling or why I now bring this totally different "toy" into the topic ! ! !

Maybe JudoP became confused about naming the "distances", that in graphics usually are named as "r" (as "route"), but in my drawings are not named "r" but "v" as "velocity". But in case of my drawings this is because the large circle, respectively its circumference, exactly represents one round of bullet (or sling) within "1/3 second" (because the initial-velocity was "3 rps") and is known for its amount (= 7,5 m - okay, I forget to tell that in the drawing too).

So while keeping this "proportions" and always knowing the "run time" from each position (of ball & hand) my nowhere named "r" is the same as "velocity v" because "r/t" (amount of route per "run-time-difference" - means: The time / run time you always can read from balls non-accelerated travel on its non-accelerated circle). In other words: My drawn "routes" are velocitys.

I have done this because my attention is to draw this drawings like / as a "story-book" for an "animated GIF" where I practically need 24 or 36 frames per ROUND (!) what than shall represent a balls run while 1/3 second. So the distance or "route" between "ball in position P0 and ball in position P1 ..." exactly is 0,0138 second ... (!) ... as long as the ball runs not accelerated but with 22 m/s only (= initial velocity !). But when the ball (or balls running-circle) gets accelerated then even that "extra routes per second" I can construct and mesure in the drawing.

That's like to have a "ruler" that can not mesure the distance only but also the time, because time and distance is here the same. That's right like a clock, where the second is exactly "one millimeter" - when the top of the second finger runs for one millimeter then exactly one second "wents" (is gone).

EACH CLOCK or WATCH is like a proof for my claim, that a special "distance" may be taken as / or for "time", and right here this method is not a sign of my "un-knowledge in physics" but "clever" and a very important part of the whole "solution of a miracle".

The only difference between my drawn sling-dynamic and a clock is the "scale" and the phenomenon that the second-finger suddenly starts to run faster and accelerates more and more (while another clock still shows the "non-accelerated time"). This "slinging-clock" of course runs extremly more faster than a (second-finger in) a real clock, because the sling runs one complete round in 0,333 seconds only.



My next drawing (Image P-04) shows how it comes to a stagnation in a balls accelaration while running to / crossing the south-point (because "v hand effectiv" becomes smaller although hands velocity "v Hand" becomes greater) ... and how this is to construct in these kind of graphics.solution of a miracle

---

But please note before much talking and posting about this: I also will post the images "Image P-05", "Image P-06" and some more for complete and explain the same "story". So please chat about my "stupidity in physics and / or mechanics" first then when have seen the whole story and its "(happy) end" or "(real / correct) result".

Otherwise I have to post all images once more for keeping them in a "non hacked" together hang.


... ähm ... autsch! - Right now I note an other kind of mistake: I added hands full amount of velocity to the balls velocity, although I wanted to add only the amount of "v hand effectiv" (... so "77 m/s" is much to much here!). Also it is not realy "the  end in hands second stage" but "hands third stage". BUT DON'T WORRY - this mistakes hits not the drawing or construction but the amount of written "77 m/s" and another text only. The construction itself is correct!

Okay - "the same procedere as every year": I will correct this and upload anew in a couple of hours (becaus first I have to go for shopping and hurry up).

Also NOTE: I am not absolutely sure if it is correct to say: "ball and hand each have its own inertial-system (that are coupled by the sling"), because what I have read in Wikipedia about (germ.) "Inertialsystem" (= Bezugssystem) and a "inertial system besides another inertial system" sounds pretty "worryfying" - so of course I could have read / understood this not totally correct.


EDIT: CORRECTED NOW! Velocity of ball in this stage / position is not "77 m/s" (as I wrote at first) but "66 m/s" only. The small circle arround the "hand" (color: magenta) allows to estimate "v hand effectiv" very easily: It's a little more than 50% of "v Hand" (means: 51 - 52 % of 28 m/s).

"Probably" the same mistake (= to sum up to much) I made in my drawings before this one, but there this mistake effects not so much, that I had to correct it right now, because here at the most I want to show the principle of construction only. For the mentioned "animated GIF" I have to draw it anew and more precisely anyway. So for now and this it is still precise enough. Also I think I was taken too less of speed / acceleration for hands move - so in "reality" the real acceleration would run just like I had it drawn now nevertheless.

JudoP wrote on Aug 28^th, 2017 at 11:35am:

[quote author=54766B697160190 link=1502880716/72#72 date=1503925229]In situations like this you can save a ton of time by doing a video first. Isnt it possible to sling at a brick wall and use Audacity to get a rough estimate on release velocity? Even if its 30 meters away with tungsten there will be virtually no loss of velocity. Once you have a release speed that proves these numbers you guys can then focus on how its possible instead of whether it is or not. I dont know much about the physics end but it seems like you guys can argue for another 10 pages and you wont convince each other.  :P

This would be a valuable experiment to run for sure, but alas- the argument was already about how it's possible (or more generally how the sling produces speed) rather than whether or not it is  :-[/quote]

I see. I must have stopped reading before you guys reached that consensus.

To continiue the construction story "Image P-01 until Image P-05" I have to break down here, because I have discovered too much faults in it's beginning or "base":  :'(

1. "V Ball" (Velocity of ball) was not drawn in the correct proportion to the "step-width" (its lenght is allowed to reach from "P-1" to "P 0" only).
2. Step-width of hands extension in the beginning I choosed to high and choosed to low in its last stage(s).

Nevertheless I still want to show you the Image P-05 for showing the construction of Position "P 4" in this angle of sling: "v hand effectiv" is to subtract from "v relative", respectively from "v Ball" (= v relative from previous stage), but "v Ball at true path" is increasing nevertheless (due to the "galilei tranformation"). I still don't know how to express this in the drawing only.  :-/

From here on I will start to draw the "story" anew once more  :D, but posting (upload) it first when will have it completed  8-).

---

JudoP wrote on Aug 27^th, 2017 at 11:27am:

Quote: I think about Einsteins "realativity" you are thinking to much "exotic". His relativity isn't no other than a absolutly common relativity as is called also "proportion" or "relation (-ship)" ... for example.  No, it's totally different. Einstein's relativity is exotic and turns traditional notions of frame of reference on their head.Different reference frames and the idea of 'relativity' have been around as long as mechanics. Since Newton at least.

Judo P - Sorry for remembering to this old thread, but I found this on Wikipedia (german) and then in english too. Maybe this can solve a misunderstanding that is only caused by differences in language:

https://en.wikipedia.org/wiki/Acceleration


Relation to relativity / Special relativity / General relativity

"Unless the state of motion of an object is known, it is impossible to distinguish whether an observed force is due to gravity or to acceleration—gravity and inertial acceleration have identical effects. Albert Einstein called this the principle of equivalence, and said that only observers who feel no force at all—including the force of gravity—are justified in concluding that they are not accelerating.

(The special theory of relativity describes the behavior of objects traveling relative to other objects at speeds approaching that of light in a vacuum. Newtonian mechanics is exactly revealed to be an approximation to reality, valid to great accuracy at lower speeds. As the relevant speeds increase toward the speed of light, acceleration no longer follows classical equations.

As speeds approach that of light, the acceleration produced by a given force decreases, becoming infinitesimally small as light speed is approached; an object with mass can approach this speed asymptotically, but never reach it.)"





Wikipedia / Beschleunigung (german): https://de.wikipedia.org/wiki/Beschleunigung

Äquivalenzprinzip und allgemeine Relativitätstheorie

"Das Äquivalenzprinzip besagt, dass in einem frei fallenden Bezugssystem keine Gravitationsfelder existieren. Es geht auf die Überlegungen von Galileo Galilei und Isaac Newton zurück, die erkannt haben, dass alle Körper unabhängig von ihrer Masse von der Gravitation gleich beschleunigt werden. Ein Beobachter in einem Labor kann nicht feststellen, ob sich sein Labor in der Schwerelosigkeit oder im freien Fall befindet. Er kann innerhalb seines Labors auch nicht feststellen, ob sein Labor gleichförmig beschleunigt bewegt wird oder ob es sich in einem äußeren homogenen Gravitationsfeld befindet.

(Mit der allgemeinen Relativitätstheorie lässt sich ein Gravitationsfeld durch die Metrik der Raumzeit, also die Maßvorschrift in einem vierdimensionalen Raum aus Orts- und Zeitkoordinaten ausdrücken. Ein Inertialsystem hat eine flache Metrik. Nichtbeschleunigte Beobachter bewegen sich immer auf dem kürzesten Weg (einer Geodäte) durch die Raumzeit. In einem flachen Raum, also einem Inertialsystem, ist dies eine gerade Weltlinie. Gravitation bewirkt eine Raumkrümmung. Das bedeutet, dass die Metrik des Raumes nicht mehr flach ist. Dies führt dazu, dass die Bewegung, die in der vierdimensionalen Raumzeit einer Geodäte folgt, im dreidimensionalen Anschauungsraum vom außenstehenden Beobachter meist als beschleunigte Bewegung längs einer gekrümmten Kurve wahrgenommen wird.)"


The german version shows this image for imagination (and I mean that both situations also can be "combined" - therfore I said "speed is relativ" and ment: "velocity in counter-directions can be added"):

---

Apex-apoc wrote on Oct 15^th, 2017 at 2:32pm:

it is impossible to distinguish whether an observed force is due to gravity or to acceleration

if i remember correctly you compared force caused by gravity to the force caused be the slingers arm.
this needs further explanation because force caused by gravity is  ~1/r^2
while force caused by the arm(or body) is more complex, a whole system of bones (levers) and muscles .

the direction of the force( F~1/r^2) on a planet in an ellipsoid orbit is always on the line connecting the planet and one focus of the ellipse.

the direction of the force in slinging is always on the line connecting the hand and the projectile, and F is not  ~1/r^2 (also r is a constant=sling length)

Apex-apoc wrote on Oct 15^th, 2017 at 2:32pm:

JudoP wrote on Aug 27th, 2017 at 11:27am: Quote: I think about Einsteins "realativity" you are thinking to much "exotic". His relativity isn't no other than a absolutly common relativity as is called also "proportion" or "relation (-ship)" ... for example.  No, it's totally different. Einstein's relativity is exotic and turns traditional notions of frame of reference on their head.Different reference frames and the idea of 'relativity' have been around as long as mechanics. Since Newton at least. Judo P - Sorry for remembering to this old thread, but I found this on Wikipedia (german) and then in english too. Maybe this can solve a misunderstanding that is only caused by differences in language: https://en.wikipedia.org/wiki/Acceleration Relation to relativity / Special relativity / General relativity "Unless the state of motion of an object is known, it is impossible to distinguish whether an observed force is due to gravity or to acceleration—gravity and inertial acceleration have identical effects. Albert Einstein called this the principle of equivalence, and said that only observers who feel no force at all—including the force of gravity—are justified in concluding that they are not accelerating. (The special theory of relativity describes the behavior of objects traveling relative to other objects at speeds approaching that of light in a vacuum. Newtonian mechanics is exactly revealed to be an approximation to reality, valid to great accuracy at lower speeds. As the relevant speeds increase toward the speed of light, acceleration no longer follows classical equations. As speeds approach that of light, the acceleration produced by a given force decreases, becoming infinitesimally small as light speed is approached; an object with mass can approach this speed asymptotically, but never reach it.)" The german version shows this image for imagination (and I mean that both situations also can be "combined" - therfore I said "speed is relativ" and ment: "velocity in counter-directions can be added"):

Hi Apex, long time no speak  ;) Unfortunately I think the disagreement still lies. The stuff around Einstein's work (though extremely interesting) still cannot contribute meaningfully to this problem.

Einstein's relativity cannot bear any relevance unless motion was happening at near light speed, or the concentration of energy/mass is so high that significant curvature of space-time would occur. In our (relatively) low-speed, low-mass world, all relativistic effects are essentially zero and the world can therefore be assumed to be Newtonian.

I believe the argument you are making is from something along the lines of a Galilean transformation, which relates to the concept of relativity (before Einstein made it bizarre).

However, the Galilean transformation is only a reference frame transformation. It has no predictive power, it only tells us how different viewpoints will perceive different positions and motions.

For example, if you were to say that from the perspective of your body, your hand is moving 20m/s... And from the perspective of your hand, the sling projectile is moving 30m/s. It would be factually true to state that the sling projectile is moving 50m/s relative to your body, the earth etc (assuming directions line up).

The problem is that this is just a consistent picture of multiple observations of a given situation. It merely returns relative motions given other relative motions. It does not characterize how a system is affected when a force or motion is made, it just gives a consistent picture at all times for all observers.

Essentially the sticking point is that there is an implicit assumption in your method- that you can simply isolate and move around the spinning sling 'system' without affecting it's internal behavior in any way.

Realistically, all you can do is apply force from the loop end of the sling. This causes an acceleration of the sling projectile due to the tension along the sling. It is what (in combination with a tangential velocity) causes the circular rotation. Altering the force magnitude and direction necessarily alters the motion of the sling projectile. It's new path is determined by it's current velocity and the new altered acceleration due to the force applied through the arm and hand.

JudoP wrote on Oct 16^th, 2017 at 2:14pm:

Unfortunately I think the disagreement still lies. The stuff around Einstein's work (though extremely interesting) still cannot contribute meaningfully to this problem.

But Wikipedia thought that it could contribute: "Relativity" is here only one header underneath the header: "Acclerartion". A thread or theme underneath is Einsteins "principle of equivalence".

I never spoke from "all the stuff around Einstein's work / calculations and effects of special relativity" but from Einsteins imaginition of passenger in or out of a field of gravity or an acclerated elevator or "labour room".

I spoke from "intertial accleration" and that it is not clear if it's forces (or effects) are the same like from "gravity". This theme or "problem" is generally connected with Einstein, respectively with Einsteins "work and theory". Not only the "special or general relativity" is one of his "fruits". Einstein said, that he doesn't know (or that he thinks) if effects of acceleration and effects of gravity (not) are the same effects (today this question isn't to answer for sure).

So I do not understand why always you track mental connections to "special relativity". I wanted to talk about ACCELERATION vs. GRAVITY ... not about effects of "traveling with speed of light while riding a photon"!

johan wrote on Oct 15^th, 2017 at 4:14pm:

if i remember correctly you compared force caused by gravity to the force caused be the slingers arm.

Hello! The force of arm in the first line causes acceleration - independent of its complexity. Therefore it is part of a "motion apparatus".

"Complex" are already the movements within metabolic processes, macro-molecules, molecules and atoms. Probably the movements of the last ones (higgs particle / photons?) causes gravity, respectively, acceleration.

So I would say, not the arm causes gravity, but (his) movement, and movement generally, because: Where is no movement, there also is no mass. Moveless particles, mass, masses or a lot of moveless particles never was seen until today.


Mass is movement, and if it wouldn't move than it wouldn't be mass.


But how should it move from A to B without leaving B?

It is conspicious that gravity is right not only a "positiv force", because a "moon" that comes closer to planet "A" has to remove from planet "B". That cannot be called as "tracking (tractor / attraction) between moon and planet A".

You always have to ask "what planet" too: Planet A or planet B ... ? ... mass A or mass B or mass C?

So there never is only "mass appeal" but also "rejektion" at the same time. The one phenomenon cannot appear without the other, and therefore even S. Hawkings, collegs and "prof. Dr. Dr. SC Super-Clever" sees and tells that wrong: Gravity is right NOT the only "positiv" force, while all other forces are "bipolar" (positiv & negativ). That's only the physicans most modern "non-sense".


Sir Isaak Newton said (after watching the dropped apple): All "apples" only fall down / downwards - there have to be an appeal ("mutual attraction"?) between the mass of apple and mass of earth".

But he was wrong, because relative to the moon or sun above the apple-tree, the same apple doesn't falling down but "up" or "upwards".

Newton only opens one more Question: How was apples came up the trees, if appels could only fall down ???


In history of science right Newtons claim is the oldest, silliest and biggest lie / error ever. The truth is: You can not went to Chicago without leaving Manhatten! That is not a mystik "tracking" or mass-appeal, but a totally simple "going", progress or move.

And sure: Nowadays we know how masses come up the sky, the mountains and the trees, and we gave that forces different names, but that nevertheless are forces that are founded on gravity. Even "buoyancy force" depends on gravity, and so finally it is gravity that lifts apples up the trees. They do not falling down "because of gravity" but because the medium that sourrounds the appels has lower density than the apples. Otherwise they would fall UPWARDS "because of gravity"!

The lowest and highest density you can find in space, but its masses are not "attracted" by locals (centers) of highest density, but highest densitys are formed by (irregular) movements of mass(es). And finally:

Some photons way isn't curved because (the nearness) of a mass centre, but absolutly independent of its existence. Some photons return because of its curvy path, and some do not. But colliding and fusing with other photons on locals that we have called "near" or "nearness" (watchable space / galaxys) can only that ones with curvy paths, because other photons never returns. Other photons passed "near" locals long long ago a will never come back, and others will pass our local first when we had been gone (disappeared) at the longest. 

Not only speed, time, age, nearness and distance are "relative", but curvyness (radius) and "turning sense" too. So it is absolutly logical, that you in the "near" only can find that kind of stuff, that collides and forms locals of highest density, because all other kind of stuff (mass / matter) is out of "reach" at the longest. OF COURSE that stuff is right not "here" and was (had?) never been seen. "Here and now" is only that stuff with curvy path(s) (relativ small turning radius) surrounding some centres of mass. Right caused by the curvyness of particles pathes the number of collisions and fusions increases within that short time that we can wait and become AWARE.
   
Difficult to understand is only why or how a photons radius of return becomes more and more smaller with each collision. But if that has been understood, then gravity (nature and inertia of mass) has been understood too.


Maybe your walk for Manhatten is biomechanically very complex, but under the line it is nevertheless a totally simple run for Manhatten stright on along the highway: One simple run from A to B.

_______________________________________________________________________________

Im Deutschen sagt man auch: "... Cäsar ZOG über den Rubicon ..." - das tat er allerdings freiwillig, und nicht etwa "gezogen", gezwungenermaßen, gedrückt oder "geschoben" wegen einiger "Schub- oder Anziehungskraft" von Seiten dessen, was "das ander Ufer" oder "die andere Seite" heißt. Er hat den Rubicon halt einfach überquert, und zwar allein von sich aus, wenn auch nur mit Gottes Hilfe oder ausreichend viel Schub~ oder Tatkraft die er in Gestalt von Kalorien einer Nahrung entnommen hatte.

Alle Masse / Materie ist schon allein von sich aus auf einem mehr oder minder krummen Weg nach irgendwohin, denn andernfalls wäre sie auch schon gar keine Masse oder Materie.

Noch zu ergänzen wäre allenfalls, dass Masse wie Menge halt ein allerhöchst abstrakter Begriff ist, da man faktisch nicht sagen kann, wo sie anfängt oder endet. Alle Massen sind umstellt und umringt von noch viel mehr Massen. Wo soll sie also im positiven Sinne "HIN", wenn nicht auch zugleich "WEG" von anderen Massen im negativen Sinne?

"Halb zog sie ihn, halb sank er hin". Der Vergleich damit hinkt nun zwar, aber passend find ich diese Verszeile trotzdem.mutual attractionmutual attractionmutual attractionmutual attractionmutual attractionmutual attraction

Apex-apoc wrote on Oct 17^th, 2017 at 9:57am:

Hello! The force of arm in the first line causes acceleration - independent of its complexity. Therefore it is part of a "motion apparatus". "Complex" are already the movements within metabolic processes, macro-molecules, molecules and atoms. Probably the movements of the last ones (higgs particle / photons?) causes gravity, respectively, acceleration. So I would say, not the arm causes gravity, but (his) movement, and movement generally, because: Where is no movement, there also is no mass. Moveless particles, mass, masses or a lot of moveless particles never was seen until today. Mass is movement, and if it wouldn't move than it wouldn't be mass. Also it is conspicious that gravity is right not only "positiv", because a "moon" that comes closer to planet "A" has to remove from planet "B". That cannot be called as "tracking (tractor / attraction) between moon and planet". You always have to ask "what planet" too: Planet A or planet B ... ? ... mass A or mass B or mass C? So there never is only "mass appeal" but also "rejektion" at the same time. The one cannot appear without the other, and therefore even "S. Hawkings" and "prof. Dr. Dr. SC Super-Clever" sees and tells that wrong: Gravity is right NOT the only "positiv" force, while all other forces are "bipolar". That's only the physicans most modern "non-sense". Sir Isaak Newton said (after watching the dropped apple): All "apples" only fall down / downwards - there have to be an appeal between the mass of apple and mass of earth". But he was wrong, because relative to the moon or sun above the apple-tree, the same apple falls "up" and "upwards". In history of science right Newtons claim is the oldest, silliest and biggest lie ever. The truth is: You can not went to Chicago without leaving Manhatten! That is not a mystik "tracking" or mass-appeal, but a totally simple "going", progress or move. Maybe your go for Manhatten is biomechanically very complex, but under the line it is nevertheless a totally simple go for Manhatten stright on along the highway: One simple run from A to B.

you are saying a mass can push (repel) another mass with gravity? (antigravity?)
you either are confused or a troll with a lot of time and resources ;D .
where did you learn physics? just curious.
the only thing that can prove a theory false is real data-life- experiments, so
what experiment can i do to replicate your results (repelling gravity)?

johan wrote on Oct 17^th, 2017 at 12:24pm:

you are saying a mass can push (repel) another mass with gravity? (antigravity?)

Never felt the pressure under your feet? Thats caused by gravity, and first if you are playing "cliff hanger" you would feel the same gravity as pulling or a pull, you troll! ;D

A lot of people died under the weight (!) of heavy masses of scree - they was not torn (apart), but CRUSHED (or "pushed").


Where did you learn thinking? In greece, perhaps?



johan wrote on Oct 17^th, 2017 at 12:24pm:

... what experiment can i do to replicate your results (repelling gravity)?

Probably not only one, because you do not notice anything  ;D   (... also "attraction gravity" never was "replicated" - neither by you nor by anyone. "Gravity" - lat.: "gravitas" - means not "attraction force" but "heavynes" / "inertia" / "severity").


So my tipp to you: Try it once more with more friendly words!

maybe you want to modify this reply too...

johan wrote on Oct 18^th, 2017 at 9:34am:

maybe you want to modify this reply too...

"Too"? Who else modified (or want to modify) his reply???

That you prefer (want) the more aggressiv formulated reply doesn't go without notice!

This thread.. is.. insane.. I have no idea how one can follow it, I am just a caveman with a piece of string
its way above me

AncientCraftwork wrote on Jul 9^th, 2020 at 11:05am:

This thread.. is.. insane.. I have no idea how one can follow it, I am just a caveman with a piece of string its way above me

:D Don't even try. This convo got very dragged into the weeds and blew up with lots of stuff that isn't even relevant.

Noooooooooooooo put this thread back in the archive

Mersa wrote on Jul 9^th, 2020 at 7:19pm:

Noooooooooooooo put this thread back in the archive

No! Don't do that yet.

I missed most of this at the time, and I feel the arguments that were being made were along the right track.

A very long time ago there was a paper by "George Alsation" accessible. I can't seem to locate a non-Forum home page, which existed at one time. That contained a number of little examples trying to get to grips with the mechanics of the sling, and Apo's diagrams seem to have been illustrating one of Alsation's points.

It looks to me like the dialog between him and JudoP broke down over the description of forces and (probably) some language matters.

The nub of all this is that to increase the speed (kinetic energy) of the sling stone you have to do work on the 'hand' end - what would be the support point if this were a 'high school physics' simple pendulum.

For that you need to move the support point (the hand) , and you also need the pendulum bob to be traveling in a curve in order to tension the cord. If you move the support point appropriately you couple energy into the slingstone and hence increase its speed.

On Apo's diagrams, he was dealing with the motion of the slingstone from W (west) via S and then finally to E, or thereabouts. Throughout this region the sling is pulling against the hand such that movement of the hand towards the north (as Apo was describing) will do mechanical work on the system, increasing the sling stone speed.

Apo also touched, as far as I can make out, on the view of the sling as like a simple pendulum where instead of just a constant gravitational acceleration there is instead a variable acceleration which is due to the movement of the support point. This view is confirmed if you grind through to the Lagrange equation of motion.

I have to admit I wondered whether Apo was actually "George Alsatian", so similar was the basis of his arguments, but who knows?

Apex-apoc = Apo  ;)

wanderer wrote on Jul 10^th, 2020 at 3:58am:

A very long time ago there was a paper by "George Alsation" accessible.

This one?

http://web.archive.org/web/20070101032007/http://www.slinging.org/29.html

wanderer wrote on Jul 10^th, 2020 at 3:58am:

Apo also touched, as far as I can make out, on the view of the sling as like a simple pendulum where instead of just a constant gravitational acceleration there is instead a variable acceleration which is due to the movement of the support point. This view is confirmed if you grind through to the Lagrange equation of motion.

I dont remember an article like that in this discussion, if you find it please post it again or post the reply#.(I dont have the time to go through it again right now)
The only thing Ive seen close to what you describe is http://slinging.org/forum/YaBB.pl?num=1561512843 reply#4


NooneOfConsequence wrote on Jun 26^th, 2019 at 8:28am:

For some reason part of the link cut off. Top result here: https://scholar.google.com/scholar?hl=en&as_sdt=0%2C44&q=flinger+trebuchet

haven't read it yet, I still need to up my physics game.

Jauke ich bin auch ein Höhlenmensch. Lass uns slingen gehen. Theorie ist für Theoretiker. Slingen ist was für Höhlenmenschen. 😁 😂

Sarosh wrote on Jul 10^th, 2020 at 4:27am:

I dont remember an article like that in this discussion, if you find it please post it again or post the reply#.(I dont have the time to go through it again right now) The only thing Ive seen close to what you describe is http://slinging.org/forum/YaBB.pl?num=1561512843 reply#4

It's the one Teg just posted. Strange how I never have the wayback machine at the front of my brain for these things.

The paper you posted looks like a barrel of laughs. Perhaps the culmination of several semesters of classical mechanics.  ;)

But... equation (12) in there is the one I had in mind, but maybe looks less offensive in polar coordinates.

wanderer wrote on Jul 10^th, 2020 at 3:58am:

The nub of all this is that to increase the speed (kinetic energy) of the sling stone you have to do work on the 'hand' end - what would be the support point if this were a 'high school physics' simple pendulum. For that you need to move the support point (the hand) , and you also need the pendulum bob to be traveling in a curve in order to tension the cord. If you move the support point appropriately you couple energy into the slingstone and hence increase its speed. On Apo's diagrams, he was dealing with the motion of the slingstone from W (west) via S and then finally to E, or thereabouts. Throughout this region the sling is pulling against the hand such that movement of the hand towards the north (as Apo was describing) will do mechanical work on the system, increasing the sling stone speed.

What you say seems correct to me, the contention was that you cannot simply add v_hand to the current angular velocity of the sling projectile. In fact you cannot really apply force at all in the north/south direction when the sling is in the 9 o'clock position, since the cord is orthogonal with N/S direction.

Instead you apply force inwards across the whole movement which converts into greatly increased angular velocity. It may not feel like this in practice, but if you sling you can feel the tension pulling always directly outwards along the cord, and the force you apply to the projectile via the cord is simply working against this. In fact the only force you CAN apply is radially inwards.


Quote:

Apo also touched, as far as I can make out, on the view of the sling as like a simple pendulum where instead of just a constant gravitational acceleration there is instead a variable acceleration which is due to the movement of the support point. This view is confirmed if you grind through to the Lagrange equation of motion. I have to admit I wondered whether Apo was actually "George Alsatian", so similar was the basis of his arguments, but who knows? Apex-apoc = Apo  ;)

It does seem likely in reading both posts. The sling has a lot of similarities with a pendulum, it is basically the same system with different forces applied. It seems plausible to me that the movement (acceleration specifically) of the support point could be reformulated as an external (pseudo) force, though you may see extra complication as I expect that the pivot hand force will change through time to be applied directly along the line of the sling, compared to gravity which is a constant. Overall this seems a much more promising approach than what I think he was trying to explain to me around adding velocities. Unfortunately I think any allusion to this was lost in translation for the original thread.

Oh no. What have you done? Cast it into the fire! Destroy it!

But seriously, I stopped even trying to follow this one.

Teg wrote on Jul 10^th, 2020 at 4:26am:

wanderer wrote on Jul 10th, 2020 at 3:58am: A very long time ago there was a paper by "George Alsation" accessible. This one? http://web.archive.org/web/20070101032007/http://www.slinging.org/29.html

LOL ...Ok, I probably enjoy the theory discussions more than most people, but it’s hard to take this seriously when his physics-based advice includes “run to the side and cover your head”

He doesn’t need math, he needs more practice!  ... and maybe a different sling.

https://i.gifer.com/9O6Z.gif

Ah my favorite thread, this video is great for studying sling slowmotion shots, I can watch it over and over
https://youtu.be/qm--RIJH0p0

Can someone start a tangent on this thread about which is worse for society hunting with the sling or socialism? Apparently this thread needs to go nuclear before it can be locked and forgotten. Seriously, this is one of the most painful to read threads on this site.