This discussion confirms that it is indeed possible for an object to rotate about two axes simultaneously through the application of torque, which is mathematically defined as the cross-product of two vectors: 𝑇=𝑟×𝐹. The conversation highlights that while a gymnast or diver appears to rotate in two axes, they are effectively rotating around a single, combined axis of rotation. The discussion also emphasizes the importance of understanding angular velocity decomposition and the role of torque in achieving complex rotational movements.
Physics students, gymnastics coaches, athletes, and anyone interested in understanding the mechanics of rotation and torque in dynamic movements.
No. The notion of "rotation" does not apply.Sundown444 said:So, they can rotate around any axis/number of axes, then?
jbriggs444 said:No. The notion of "rotation" does not apply.
The motion of a non-rigid object cannot always be described as a rotation. Sometimes it's just "squishing" or "swirling".Sundown444 said:So they are not really rotating, something like that?
jbriggs444 said:The motion of a non-rigid object cannot always be described as a rotation. Sometimes it's just "squishing" or "swirling".
russ_watters said:I really think this is going down an unnecessary road. @Sundown444 you seem to be deviating from the answer you got and seemed to understand in post #2. Why?
You didn't ask a specific question (just "how do you explain...") in your recent reboot, but yes, I too thought it was related to your first post. So why isn't the answer, "yes" (with added depth), good enough anymore? What happened? It feels like we are starting over from scratch, but all the previous posts are still there!Sundown444 said:*sigh* Wasn't aware of that. I thought the video I posted was related to my original question, due to how some of the divers rotated. In fact, those divers rotation was mainly what I was asking about to begin with. I just didn't see the need to post that video for some reason until now.
russ_watters said:You didn't ask a specific question (just "how do you explain...") in your recent reboot, but yes, I too thought it was related to your first post. So why isn't the answer, "yes" (with added depth), good enough anymore? What happened? It feels like we are starting over from scratch, but all the previous posts are still there!
Is there something you believe, but don't want to admit? Something you want to know, but don't want to ask?
Yes, the answer is still yes.Sundown444 said:No, I knew of the answers before this thread. I just wanted to make sure with this video. Double checking, that is all. That said, is it still the same answer as before?
russ_watters said:Yes, the answer is still yes.
Probably. Also, using declarative statements and direct questions would help us target our answers better. For example, when you say, "How do you explain...?" after having already received an explanation, it implies you think something is wrong with the explanation, without actually telling us what.Sundown444 said:Looks like there is all I need to know, then. Still a bit confused about the divers, though. Would looking back on previous posts on this topic help me out?
russ_watters said:Probably. Also, using declarative statements and direct questions would help us target our answers better. For example, when you say, "How do you explain...?" after having already received an explanation, it implies you think something is wrong with the explanation, without actually telling us what.
Training.Sundown444 said:What I meant, is that the divers seem to be doing somersaults and twists at the same time. If I have this down right, I wonder how it is possible?
Yes, you have relative rotations of segments. But I wouldn't say that "body rotates around multiple axes", because the body as a whole doesn't have a defined angular velocity here. However, it does have a total angular momentum vector, which is constant during the fall (ignoring aerodynamics).CWatters said:A divers body can be modeled as a set of cylinders connected together by joints that have various degrees of flexibility. This allows some body parts and groups of body parts to rotate about different axis with respect to each other. Said axis are frequently changing.
CWatters said:How about...
A divers body can be modeled as a set of cylinders connected together by joints that have various degrees of flexibility. This allows some body parts and groups of body parts to rotate about different axis with respect to each other. Said axis are frequently changing.
...well its the best summary I can manage.
If the body does not even have a rotational axis, the notion of changing its rotational axis does not arise.Sundown444 said:The body can change rotational axis
jbriggs444 said:If the body does not even have a rotational axis, the notion of changing its rotational axis does not arise.
Who knows how it appears to you. It's like explaining how colors appear.Sundown444 said:The body can appear...
Not a good description of what actually happens, as explained in post #45 on others.Sundown444 said:...rotate around more than one axis ...
A.T. said:Who knows how it appears to you. It's like explaining how colors appear.Not a good description of what actually happens, as explained in post #45 on others.
Sounds like a serial killer making space in the fridge. What's wrong with saying "relative motion of body segments"?Sundown444 said:...rearranging body parts ...
A.T. said:Sounds like a serial killer making space in the fridge. What's wrong with saying "relative motion of body segments"?