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Curving rocks (Read 821 times)
Finn Cohen
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Curving rocks
Jun 10th, 2022 at 4:33am
 
i'm wondering if anyones noticed the tendency for rocks to curve when you throw them. particularly Flat rocks when you throw a balearic type throw. i Kind of want to learn how to do this bu Questioningt i'm not having much luck.
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TOMBELAINE
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Re: Curving rocks
Reply #1 - Jun 10th, 2022 at 7:24am
 
I could be wrong. But I think :

1) All peebles revolve around their center of gravity.
2) For all peebles, the path of the center of gravity is right.

And more,

3) A flat peeble behaves like a fin in the air.
4) Aerodynamic peeble behaves like a football (non-amecican) ball with a drived path (Magnus effect).

just my idea.


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Rat Man
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Re: Curving rocks
Reply #2 - Jun 10th, 2022 at 8:26am
 
   Yes, as long as the rocks are spinning they will always curve.  Backspin makes them curve up; frontspin that you get from an underarm throw makes them curve down.  Anything other than a perfect front or backspin and they'll curve to the left or right.
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joe_meadmaker
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Re: Curving rocks
Reply #3 - Jun 10th, 2022 at 1:22pm
 
This video from IronGoober is definitely worth checking out: https://youtu.be/ESrvvBFcrWM.

I don't know if it's entirely applicable because he's slinging a ball, not a flat stone.  But it might introduce some ideas to you.
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MMF
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Re: Curving rocks
Reply #4 - Jun 10th, 2022 at 8:11pm
 
Any spinning object in flight can experience the Magnus effect. For a flat rock, this effect may be very small. Instead, the curving you are seeing is a result of drag. The stone is taking the path of least resistance. While it is tumbling in flight, that direction changes.
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Archaic Arms
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Re: Curving rocks
Reply #5 - Jun 11th, 2022 at 3:53am
 
The rounder, the heavier your projectile is, the less the magnus effect will pull it off target. Most important thing is putting rifle-spin onto the projectile if you want to hit things past 30m.
Flat stones curve a lot to the right when you throw them at medium range, but they also release a bit later than rounded ones, so to hit the target, you have to be aware they can cancel each other out to some extent.
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Lewis
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TOMBELAINE
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Re: Curving rocks
Reply #6 - Jun 13th, 2022 at 4:43am
 
joe_meadmaker wrote on Jun 10th, 2022 at 1:22pm:
This video from IronGoober is definitely worth checking out: https://youtu.be/ESrvvBFcrWM.


Very good video, Irongoober. Clear and educational.  Smiley
Thanks
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Mersa
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Re: Curving rocks
Reply #7 - Jun 14th, 2022 at 6:02pm
 
If you want to curve rocks choose a less dense rock. Limestone with lots of internal cavities will curve heavily
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IronGoober
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Re: Curving rocks
Reply #8 - Jun 20th, 2022 at 1:33pm
 
TOMBELAINE wrote on Jun 13th, 2022 at 4:43am:
joe_meadmaker wrote on Jun 10th, 2022 at 1:22pm:
This video from IronGoober is definitely worth checking out: https://youtu.be/ESrvvBFcrWM.


Very good video, Irongoober. Clear and educational.  Smiley
Thanks

Thanks!
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John R.
 
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Tomas
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Re: Curving rocks
Reply #9 - Jul 13th, 2022 at 3:54am
 
Flat, pointy trapezoid rocks will not only bend but actually corkscrew through the air.
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IronGoober
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Re: Curving rocks
Reply #10 - Jul 13th, 2022 at 1:59pm
 
I love a good cork screw throw. Not very accurate, but very fun to watch
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John R.
 
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Re: Curving rocks
Reply #11 - Jul 13th, 2022 at 6:10pm
 
IronGoober wrote on Jul 13th, 2022 at 1:59pm:
I love a good cork screw throw. Not very accurate, but very fun to watch

Yeah absolutely. I imagine it would be really hard to dodge too if was coming straight at you. I've seen handgun bullets very visibly do the same thing, which I found rather surprising. I'd like to exactly why it happens sometimes, and why it doesn't other times.
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IronGoober
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Re: Curving rocks
Reply #12 - Jul 13th, 2022 at 6:51pm
 
I think it has to do with a precession of the spin axis. Gyroscopes precess, and I would assume a sling bullet/rock  would as well, especially given the forces/torques applied to it as it flies through the air (which will speed up the precession).

It is like a spinning top starting to wobble. I think that is the effect that causes the corkscrew. The precession of the spin axis causes different Magnus force directions/magnitudes so the stone curves, but continuously changing direction.
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John R.
 
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Druid

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Re: Curving rocks
Reply #13 - Jul 14th, 2022 at 7:40am
 
It’s definitely to do with the Magnus effect and aerodynamics. The precession might magnify the effect even more.

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Razor glandes, Aim for the eyes!!!
 
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