#81  
Old 07-08-2019, 04:37 PM
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sidewinder22 sidewinder22 is offline
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Originally Posted by SonicGuy View Post
You are reaching (pun intended). There is no way that the force used to resist gravity is causing your tendons to lose elasticity. And even if it was it would act the exact same way on an extended arm.

Honestly I find your grasp of Newtonian physics to be tenuous. Mine is as well but you are the one proposing to educate here. At this point I am willing to say your idea of "dynamic coiling" is pseudo science until proven otherwise.
Lol, ok chief.

Swinging the arm in a pendulum back and forth takes zero arm muscle, just a regular pendulum with a ball on string. If you are moving your body back and forth or spinning around, your arm/s will swing out loose and taut from the G-forces created.
https://www.youtube.com/watch?v=W2eWfwpahfk&t=52s
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  #82  
Old 07-08-2019, 05:00 PM
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Originally Posted by VictorB View Post
It's more commonly referred to as a 'stretch reflex' and it's a very real term (just used a lot more in resistance training than anything else)

also known as stretch-shortening cycle
That is fine, but whips don't have tendons so this is completely off topic.

And even if it was on topic, why would you not be able to load a tendon when the arm is pre-coiled? The answer is of course that you can load a tendon from either position, but with your arm straight back you have the advantage of using all that mass behind the tendon to do the loading.

None of this even remotely applied to the pure voodoo of "dynamic coiling" as described by sidewinder.
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Old 07-08-2019, 05:03 PM
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Originally Posted by sidewinder22 View Post
Lol, ok chief.

Swinging the arm in a pendulum back and forth takes zero arm muscle, just a regular pendulum with a ball on string. If you are moving your body back and forth or spinning around, your arm/s will swing out loose and taut from the G-forces created.
https://www.youtube.com/watch?v=W2eWfwpahfk&t=52s
Of course it will. Whether you start with your arm extended or coiled. You can get the same exact pendulum action starting from either position. You just get more force starting with an extended arm because the mass is further away from the center.

I don't understand why you are posting something that goes directly against your novel theory of "dynamic coiling".
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  #84  
Old 07-08-2019, 05:52 PM
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sidewinder22 sidewinder22 is offline
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Originally Posted by SonicGuy View Post
Of course it will. Whether you start with your arm extended or coiled. You can get the same exact pendulum action starting from either position. You just get more force starting with an extended arm because the mass is further away from the center.

I don't understand why you are posting something that goes directly against your novel theory of "dynamic coiling".
If you start pre-coiled and you never "reachback" like Dave Dunipace's video suggests, then you are not getting the same pendulum action.

If you start with the arm extended away the mass is further away, but the real key is that you can accelerate it more and change the direction of the acceleration more. Force = Mass x Acceleration. Your joints will bend/coil dynamically when your body accelerates/changes acceleration and the arm/disc lags.

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Old 07-09-2019, 09:38 AM
DG_player DG_player is offline
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Originally Posted by SonicGuy View Post
I believe the video, and I also believe you are mistaken

When you stretch out a rubber band, some of the potential energy is lost as the rubber band deforms. As you hold a rubber band stretched out, it is continually deforming, and losing its elasticity. In order for this to happen the energy in the system leaks via heat.

Your assertion that the heat is converted back into kinetic energy is wrong. If that were the case, one could simply heat up an elastic band to add to the kinetic energy. You would in fact have the worlds best heat exchange mechanism, and we would have no further use for turbines.

But of course that is not the case. The heat generated is lost forever from that system as soon as it is generated, there is no way to incorporate that back into the system. Instead, what is happening is that there is a continual generation of heat as the band deforms. It is not the loss of the existing heat that causes a loss of potential energy, but the continuous generation of new heat. At some point, the stretched band will be completely deformed and lose all elasticity and in turn will stop generating heat.

I would say this has nothing to do with the disc golf throw. By pre-coiling your arm you are not deforming an elastic band. Your arm, muscles, and tendons are at rest.
I'm going to agree that this fork in the discussion is completely irrelevant and has nothing to do with the disc golf throw. I'll just leave it at that, if you want to explore the physics more you can do your own research. I will leave you with this simple description from wikipedia:

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Temperature affects the elasticity of a rubber band in an unusual way. Heating causes the rubber band to contract and cooling causes expansion.[11] Stretching a rubber band will cause it to release heat, while releasing it after it has been stretched will make it absorb heat, causing its surroundings to become a little cooler. This effect is due to the higher entropy of the unstressed state, which is more entangled and therefore has more states available. In other words, the ability to convert thermal energy into work while the rubber relaxes is allowed by the higher entropy of the relaxed state.

The result is that a rubber band behaves somewhat like an ideal monatomic gas inasmuch as (to good approximation) that elastic polymers do not store any potential energy in stretched chemical bonds. No elastic work is done to "stretch" molecules when work is done upon these bulk polymers. Instead, all work done to the rubber is "released" (not stored) and appears immediately in the polymer as thermal energy. Conversely, when the polymer does work on the surroundings (such as contracting to lift an object) it converts thermal energy to work in the process and cools in the same manner as an ideal gas, expanding while doing work.
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Old 07-29-2019, 03:22 PM
RFrance RFrance is offline
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I believe this is Randy C.'s video follow up for the Dave Dunipace "Whip video." Click on the closed caption (CC) button for subtitles if you Finnish is a little rusty.


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Old 07-29-2019, 03:56 PM
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Originally Posted by sidewinder22 View Post
Lol, ok chief.

Swinging the arm in a pendulum back and forth takes zero arm muscle, just a regular pendulum with a ball on string. If you are moving your body back and forth or spinning around, your arm/s will swing out loose and taut from the G-forces created.
https://www.youtube.com/watch?v=W2eWfwpahfk&t=52s
I like a lot of what you write, and your adult attitude about many things, but your arm won't swing unless there is some muscle there. It may not be much, but it's there.

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Old 07-29-2019, 04:12 PM
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sidewinder22 sidewinder22 is offline
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Originally Posted by lyleoross View Post
I like a lot of what you write, and your adult attitude about many things, but your arm won't swing unless there is some muscle there. It may not be much, but it's there.
You can dingle your arm like a heavy wet towel hanging from the shoulder socket and whip it without using the arm muscles at all.


Arms get pulled out from centrifugal force, not the arm muscles.

Last edited by sidewinder22; 07-29-2019 at 04:15 PM.
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Old 07-29-2019, 04:39 PM
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lyleoross lyleoross is offline
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Yes, in an experimental thought exercise. In reality, there is muscle movement going on there. But before I stick my foot in my mouth, what is the value of such a discussion? I see none. The throw is very active, not passive. Even the whip of the wrist is not passive, it is a combination of active arm movement, and some active wrist snap, IMO. A completely passive wrist would flop about, like your arm experiment. It is a subtle notion that too often escapes folks who discuss this topic.

The arm movement should be such that it maximizes the position of the disc and the wrist to allow an efficient snap. That snap has elements that are both passive and active.

BTW - it is good to see that Dave is finally moving away from a passive throw to one where the mechanism moves you towards a more active process. If I understand this discussion. Perhaps not.
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  #90  
Old 07-29-2019, 06:48 PM
NoseDownKing NoseDownKing is offline
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Originally Posted by lyleoross View Post
Yes, in an experimental thought exercise. In reality, there is muscle movement going on there. But before I stick my foot in my mouth, what is the value of such a discussion? I see none. The throw is very active, not passive. Even the whip of the wrist is not passive, it is a combination of active arm movement, and some active wrist snap, IMO. A completely passive wrist would flop about, like your arm experiment. It is a subtle notion that too often escapes folks who discuss this topic.



The arm movement should be such that it maximizes the position of the disc and the wrist to allow an efficient snap. That snap has elements that are both passive and active.



BTW - it is good to see that Dave is finally moving away from a passive throw to one where the mechanism moves you towards a more active process. If I understand this discussion. Perhaps not.
I'm not saying that you are in denial, but don't trash down the fact that "using the arm as a pendulum takes zero arm muscles". It is true since you could stick a ball on a string pendulum on your shoulder right now and start swinging it with your body. Obviously there is little muscle involvement going on, but you shouldn't be thinking about it that way.

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