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Newtons as a Measure of Skill (Read 6418 times)
Pikåru
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Re: Newtons as a Measure of Skill
Reply #15 - Jan 25th, 2013 at 4:57pm
 
towelie wrote on Jan 21st, 2013 at 10:53am:
After reading all the feedback, I think maybe the formula would best be adjusted to measure the initial velocity of the gland instead of the force applied to the sling and gland. The new formula is attached as an image.

Variables are as follows:
T = Time (in seconds) from launching the gland to the highest point in the gland's trajectory.
θ = Angle of gland's trajectory at the initial launch
V = initial velocity of gland in meters per second.

To convert m/s to MPH, multiply V by 2.237



The answer is 42.

Complicated minutia. What makes a good slinger? It's a little like the Miller Test. You'll probably know it when you see it.
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LightSlinger
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Re: Newtons as a Measure of Skill
Reply #16 - Jan 25th, 2013 at 9:03pm
 
I thought 42 was the answer to life the universe and everything.. Lol
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Pikåru
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Re: Newtons as a Measure of Skill
Reply #17 - Jan 25th, 2013 at 10:38pm
 
Yes, to everything...
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I sling. Therefore I am. Tano' Hu I Islan Guahan. http://itanohu.blogspot.com
 
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GeneralMushroom
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Re: Newtons as a Measure of Skill
Reply #18 - Jan 26th, 2013 at 4:11am
 
Newtons are a unit of force (actually it's the SI unit for force). Impulse is the force multiplied by the time the force is delivered, eg. I can probably push you a lot harder than I can punch you, but because the push is delivered over a much longer time, it hurts you less.
It's difficult to use Newtons as a measure of skill, because everyone's idea of skill is different.

Skill with the sling (to me) is being able to hit your target with sufficient force to do what you want to do.

Measuring Newtons would be a much better measure of brute strength and which slinging technique is the most powerful.


It's definitely a good idea to think about, and I think people are getting too caught up in the maths to take the idea seriously.
I do engineering as a degree and I've been trying to work out the speed and force I can throw a projectile for a while now. The problem is, I don't have any decent cameras to record myself, or decent enough scales to measure masses of projectiles, so I'm going on ballpark figures and rough estimates.

When I come to some serious money, one of my first purchases would be a decent high speed camera (2,500 fps or higher) and just film myself slinging at targets for hours on end. Both for calculation, and finding flaws in my technique.
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Matt, 21. Engineering undergrad, enjoys slinging!
 
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Re: Newtons as a Measure of Skill
Reply #19 - Jan 26th, 2013 at 6:42am
 
You won't need anywhere near 2500 fps unless you want to do extremely accurate analysis. Typical release velocities are around the 50 m/s mark which would mean only 20 mm movement between frames and at the beginning of the cast it would be much less.

Here's a trace of the path of my Fig.8 I drew merely by placing some tracing paper over the screen. Camera speed was a lowly 30 fps.

Also here's the link to the actual video clip:-

http://www.youtube.com/watch?v=PKz8CcPSRu0
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Re: Newtons as a Measure of Skill
Reply #20 - Jan 26th, 2013 at 7:17am
 
Aussie wrote on Jan 26th, 2013 at 6:42am:
You won't need anywhere near 2500 fps unless you want to do extremely accurate analysis. Typical release velocities are around the 50 m/s mark which would mean only 20 mm movement between frames and at the beginning of the cast it would be much less.

Here's a trace of the path of my Fig.8 I drew merely by placing some tracing paper over the screen. Camera speed was a lowly 30 fps.

Also here's the link to the actual video clip:-

http://www.youtube.com/watch?v=PKz8CcPSRu0


I'm an engineer, I like extremely accurate analysis Tongue

Yeah, my rough analysis yielded release velocities of about 48-55m/s using a short sling in the helicopter technique. At lease I'm doing something right Wink

The main problem I'm having is that the only cameras I have access to are my phone camera (1.3Megapixels) and my laptop webcam. Both have major blurring issues with objects moving faster than walking speed.
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Re: Newtons as a Measure of Skill
Reply #21 - Jan 26th, 2013 at 4:24pm
 
The camera I used is a fairly basic unit, under $100 here in Australia. However, perhaps you can interest your Engineering Faculty in doing a little research. Nevertheless it is surprising how much can be done with only readily available equipment and little capital outlay.

You may have seen David Morningstar's slow motion clips. Strongly recommended if you haven't.

For measuring velocity let me recommend the Audacity sound recording method. Gives good results, requires only a laptop and a tape measure (the software is free).
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Re: Newtons as a Measure of Skill
Reply #22 - Jan 26th, 2013 at 6:42pm
 
Aussie wrote on Jan 26th, 2013 at 4:24pm:
The camera I used is a fairly basic unit, under $100 here in Australia. However, perhaps you can interest your Engineering Faculty in doing a little research. Nevertheless it is surprising how much can be done with only readily available equipment and little capital outlay.

You may have seen David Morningstar's slow motion clips. Strongly recommended if you haven't.

For measuring velocity let me recommend the Audacity sound recording method. Gives good results, requires only a laptop and a tape measure (the software is free).


If it's not to do with gas turbines, then my Engineering Faculty is not interested lol.
There's a possibility I'll have access to a more substantial camera set up when I'm next back in my hometown, so I'm gunna hold off from buying anything before March.

I have Audacity and use it for audio editing, how do you use it for measuring velocity?

I think I've seen 1 or 2 of David's videos from a Balearic slinging contest, I'll definitely have a look again later
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Re: Newtons as a Measure of Skill
Reply #23 - Jan 26th, 2013 at 8:21pm
 
Audacity lets you measure small time intervals accurately by recording the swish of the release and the whack of the projectile hitting the target. Spikes on the graph show up very clearly.

Here's an old thread about it:-    http://slinging.org/forum/YaBB.pl?num=1195572094/24
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Re: Newtons as a Measure of Skill
Reply #24 - Jan 27th, 2013 at 6:10am
 
Sweet! I'll have to give that a go some time soon!
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Re: Newtons as a Measure of Skill
Reply #25 - Feb 2nd, 2013 at 8:59am
 
I think you might be right about your method of measuring velocity Cudol. Although, if someone is able to do so with a single video, I think utilizing both methods of measurement wouldn't hurt.  Wink
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