Rotation of a non pivot object

  • Context: High School 
  • Thread starter Thread starter VHAHAHA
  • Start date Start date
  • Tags Tags
    Pivot Rotation
Click For Summary

Discussion Overview

The discussion centers on the concept of rotation in the context of a falling uniform stick, specifically addressing why the axis of rotation is considered to be about the center of mass (cm) of the stick. Participants seek clarification and references to understand this principle better.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant expresses confusion about why the axis of rotation for a falling uniform stick is at its center of mass, seeking references and explanations.
  • Another participant provides a link to a resource that may help clarify the topic.
  • A subsequent post indicates that the provided resource did not resolve the participant's confusion and asks for additional tips.
  • Another participant explains that the motion of a rigid body can be described as a combination of translation and rotation about an arbitrary point, noting that the center of mass is a special point where translational and rotational motions decouple.

Areas of Agreement / Disagreement

There is no consensus reached in the discussion, as participants express varying levels of understanding and seek further clarification on the topic.

Contextual Notes

The discussion highlights the complexity of understanding rotational dynamics and the specific role of the center of mass, indicating that assumptions about motion and reference points may not be fully explored.

VHAHAHA
Messages
58
Reaction score
0
my teacher told.me.that If a rotating uniform stick is falling, the axis of rotation is about the cm of the stick.
I don't understand why it is about the cm of the ball. I have searched on google and i found no answer.
Can anyone give me some reference so that I can read? Can anyone explain to me? Thank you
 
Physics news on Phys.org
Try this: http://ocw.mit.edu/courses/physics/8-01sc-physics-i-classical-mechanics-fall-2010/rotation-and-translation/two-dimensional-rotation-and-translation-dynamics/MIT8_01SC_coursenotes27.pdf
 
i have read this note
but i still can't the answer
any tips?
 
You can describe the motion of a rigid body as a combination of translation of some point fixed with respect to the rigid body and rotation about that point. That point? It's completely arbitrary. It doesn't even have to be a point on the object. It's a consequence of Euler's rotation theorem.

So why choose the center of mass? That is the one point for which translational and rotational motion decouple from one another.
 

Similar threads

  • · Replies 10 ·
Replies
10
Views
1K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 10 ·
Replies
10
Views
1K
  • · Replies 133 ·
5
Replies
133
Views
13K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 60 ·
3
Replies
60
Views
7K