Rolling without slipping and friction

Click For Summary

Discussion Overview

The discussion revolves around the concept of rolling without slipping and the role of friction in this context. Participants explore the application of a theorem related to the power of forces acting on a rigid body and its implications for understanding the work done by friction.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant references a theorem stating that the power of forces on a rigid body can be expressed in terms of net force and torque, suggesting that this leads to the conclusion that the work done by friction is zero.
  • Another participant agrees that the work of friction is zero, explaining that this is due to the negative contribution of the first term and the positive contribution of the second term in the power equation.
  • A third participant supports the idea that the work of friction is zero, providing an intuitive understanding that friction transforms translational kinetic energy into rotational kinetic energy, rather than simply stating that the work is zero due to the point of contact having zero relative velocity.

Areas of Agreement / Disagreement

Participants generally agree on the assertion that the work of friction is zero in the context of rolling without slipping, although the reasoning and interpretations of this conclusion vary among them.

Contextual Notes

The discussion does not resolve the underlying assumptions about the theorem's applicability or the conditions under which the work of friction is considered zero.

wrobel
Science Advisor
Insights Author
Messages
1,281
Reaction score
1,089
I am sorry for drawing up very old and closed posting https://www.physicsforums.com/threads/rolling-friction.150891/
but I saw this question many times and I can not understand why do not people simply use well-known theorem which says that power of the forces which are applied to a rigid body is calculated by formula ##(\boldsymbol F,\boldsymbol v_A)+(\boldsymbol \omega,\boldsymbol M_A)##. Here ##A## is a body fixed point; ##M_A## is a net torque abput the point ##A##; and ##\boldsymbol F## is a net force.
From this formula it is clear that the work of friction is equal to zero
 
Physics news on Phys.org
It is zero because the first term is negative, while the second term is equal but positive. And that's if its rolling without slipping. Am I right?
 
Well this is probably the most rigorous way to deal with why the work of friction is zero. It is also in agreement with my intuition cause what this theorem is saying ,in the case we apply it with point A being the c.o.m , is that friction takes translational kinetic energy and transforms it to rotational kinetic energy. This is the best way to understand things, cause just simply saying that the work of friction is zero, because the point of contact has zero relative velocity, is just not so appealing to me.
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
6K
  • · Replies 59 ·
2
Replies
59
Views
5K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 41 ·
2
Replies
41
Views
7K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 52 ·
2
Replies
52
Views
8K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K