Question about Rotation

[SilentSky23]

I have some questions about torque and rotation, mainly gymnastic rotations, or possibly anything. I hope this is the right subforum for this. So, the thing is, is it possible for something like a gymnast to rotate on two axes of rotation at the same time? Maybe three axes of rotation? Also, is it possible to tilt while rotating so something is rotating at a tilted angle different from being upright? And if the answer is yes to any of these questions, why is this possible?

[J.C.MacSwell]

20 minutes ago, SilentSky23 said:

I have some questions about torque and rotation, mainly gymnastic rotations, or possibly anything. I hope this is the right subforum for this. So, the thing is, is it possible for something like a gymnast to rotate on two axes of rotation at the same time? Maybe three axes of rotation? Also, is it possible to tilt while rotating so something is rotating at a tilted angle different from being upright? And if the answer is yes to any of these questions, why is this possible?

 

Assuming a solid non-deforming body:

One axis of rotation at a time (instance) though the axis of rotation can be changing continuously. When something appears to rotate about 2 axis at the same time it would be rotating about nether, but instead about a continuously changing axis.

Of course gymnasts are not non-deforming, and defining axis of rotation can get quite complicated.

 

 

 

 

Edited July 26, 2018 by J.C.MacSwell

[SilentSky23]

1 hour ago, J.C.MacSwell said:

 

Assuming a solid non-deforming body:

One axis of rotation at a time (instance) though the axis of rotation can be changing continuously. When something appears to rotate about 2 axis at the same time it would be rotating about nether, but instead about a continuously changing axis.

Of course gymnasts are not non-deforming, and defining axis of rotation can get quite complicated.

 

 

 

 

Can you explain the gymnast part a bit more, please?

[J.C.MacSwell]

1 hour ago, SilentSky23 said:

Can you explain the gymnast part a bit more, please?

A gymnast can deform, say bend at the waste, or rotate arms on a different axis from that of the body.

[Bender]

6 hours ago, SilentSky23 said:

Can you explain the gymnast part a bit more, please?

Suppose the gymnast is rotating around his vertical axis and forward for salto's. His actual rotation is a sum of the two. By pulling his arms close and stretching his legs, his rotational axis will approach his vertical axis. When he then makes himself wide and pulls his knees to his chest, his momentary rotational axis becomes almost horizontal.

[nevim]

There was another thread somewhere not that long ago asking a similar question. If I remember correctly, Swansont gave some very detailed explanations.

But I see he has answered here since I read yesterday or maybe the threads got merged.

Apologies.

Edited July 27, 2018 by nevim

[studiot]

1 hour ago, nevim said:

There was another thread somewhere not that long ago asking a similar question. If I remember correctly, Swansont gave some very detailed explanations.

But I see he has answered here since I read yesterday or maybe the threads got merged.

Apologies.

https://www.scienceforums.net/topic/112977-question-about-rotation/?tab=comments#comment-1034383

 

 

 

Two things SilentSky

Firstly it is not a good idea to name both your threads the same. Folks get confused.

Secondly I asked there and ask again for more detail for those of us who are gymnastically challenged.

Can you not post some diagrams of the manouveres you are referring to please?

[nevim]

21 minutes ago, studiot said:

https://www.scienceforums.net/topic/112977-question-about-rotation/?tab=comments#comment-1034383

 

 

 

 

Thank you Studiot.

[SilentSky23]

On 7/27/2018 at 2:30 AM, studiot said:

https://www.scienceforums.net/topic/112977-question-about-rotation/?tab=comments#comment-1034383

 

 

 

Two things SilentSky

Firstly it is not a good idea to name both your threads the same. Folks get confused.

Secondly I asked there and ask again for more detail for those of us who are gymnastically challenged.

Can you not post some diagrams of the manouveres you are referring to please?

Fine, I will show.

What I am talking about is that some of the divers that rotate in this video seem to be rotating around two axes, specifically, somersaulting and twisting at the same time. To me, anyways. What exactly are they doing when they are appearing to do that?

[J.C.MacSwell]

2 hours ago, SilentSky23 said:

Fine, I will show.

What I am talking about is that some of the divers that rotate in this video seem to be rotating around two axes, specifically, somersaulting and twisting at the same time. To me, anyways. What exactly are they doing when they are appearing to do that?

First off +1 for the video (and incredible that the diver that hit his head still managed to hit the water without seriously maiming or killing himself)

They are "rearranging" body parts about the only axis of rotation (air/wind affects aside) that they have after their feet leave the platform. This gives the "impression" of rotation about other axes. Note that any body parts can have different axes of rotation from the "system" (the body), and they can change as they are not isolated where the "system" is isolated (minor air affects aside).

Edited August 13, 2018 by J.C.MacSwell

[SilentSky23]

8 minutes ago, J.C.MacSwell said:

First off +1 for the video (and incredible that the diver that hit his head still managed to hit the water without seriously maiming or killing himself)

They are "rearranging" body parts about the only axis of rotation (air/wind affects aside) that they have after their feet leave the platform. This gives the "impression" of rotation about other axes. Note that any body parts can have different axes of rotation from the "system" (the body), and they can change as they are not isolated where the "system" is isolated (minor air affects aside).

So they are just moving their body parts around to make it look like they are rotating in other axes of rotation?

[J.C.MacSwell]

1 hour ago, SilentSky23 said:

So they are just moving their body parts around to make it look like they are rotating in other axes of rotation?

One could say that.

[SilentSky23]

50 minutes ago, J.C.MacSwell said:

One could say that.

Are you sure it is not a combination of vectors/rotation, or net rotation? If you are confused, here is what I am talking about.

https://www.physicsclassroom.com/class/vectors/Lesson-1/Vector-Addition

[J.C.MacSwell]

2 hours ago, SilentSky23 said:

Are you sure it is not a combination of vectors/rotation, or net rotation? If you are confused, here is what I am talking about.

https://www.physicsclassroom.com/class/vectors/Lesson-1/Vector-Addition

There are an infinite number of ways to break down the rotation into vectors...a number of which could be natural and/or useful...as long as the net rotation is constant unless you have external torques. So the axes of rotations you believe you are seeing are not unique in that respect. (so that can be correct if broken down properly)

[SilentSky23]

8 hours ago, J.C.MacSwell said:

There are an infinite number of ways to break down the rotation into vectors...a number of which could be natural and/or useful...as long as the net rotation is constant unless you have external torques. So the axes of rotations you believe you are seeing are not unique in that respect. (so that can be correct if broken down properly)

So, you are saying it is both breaking down rotation into vectors and rearranging body parts to give the impression of rotation about other axes?

[J.C.MacSwell]

3 hours ago, SilentSky23 said:

So, you are saying it is both breaking down rotation into vectors and rearranging body parts to give the impression of rotation about other axes?

You can break down a simple spin into vectors, say x,y, and z axis components. I don't think that will give you much of an impression of spin about those axes.

But you could recognize rotations of sub systems (body parts) and sum them to find the net rotation of the system (body)

[SilentSky23]

2 hours ago, J.C.MacSwell said:

You can break down a simple spin into vectors, say x,y, and z axis components. I don't think that will give you much of an impression of spin about those axes.

But you could recognize rotations of sub systems (body parts) and sum them to find the net rotation of the system (body)

So it is mainly just rearranging body parts to give that impression of rotating in more axes than one?

[J.C.MacSwell]

1 hour ago, SilentSky23 said:

So it is mainly just rearranging body parts to give that impression of rotating in more axes than one?

I would say so. I am impressed with the athleticism, which I somewhat understand, and also the aesthetics...but not really sure why with the aesthetics.

[czarodziej_snow]

On 21.01.2018 at 3:34 AM, SilentSky23 said:

This should be in relation to rotational physics. Now, say you have a rotating person. Would it be possible to change axis of rotation/change direction of rotation while rotating? For example, say the person is doing a head-to-toe twist, but goes from that to a cartwheel or a flipping rotation. Would that be possible? Why or why not?

Of course it is possible for the rigid body to change the axis of rotation itself, for example, cats do it and they always fall on four legs, but it must be done in accordance with the laws of physics. This movement  describes the Euler equation of motion and the mechanism of occurrence of the internal moment of force presents this scheme.ribes

How this moment of force works during the dzanibekowa effect shows this simulation

 

 

Here is a change in angular velocities relative to body