Can Friction Cause Torque & Work on Rolling Objects?

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Discussion Overview

The discussion revolves around the role of friction in causing torque and doing work on rolling objects. Participants explore whether kinetic or static friction is responsible for these effects, particularly in the context of rolling motion and the relationship between friction and rotational kinetic energy.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question whether kinetic friction can cause torque, suggesting that only static friction might be capable of this.
  • Others argue that kinetic friction can indeed cause torque if the line of action of the friction force does not pass through the center of mass.
  • There is a proposal that static friction can do work on a rolling object, with the reasoning that an increase in rotational kinetic energy supports this claim.
  • One participant asserts that kinetic friction can create torque and rotation while sliding, challenging the notion that static friction is the only type that applies in such scenarios.

Areas of Agreement / Disagreement

Participants express differing views on the roles of static and kinetic friction in causing torque and doing work on rolling objects. The discussion remains unresolved, with multiple competing perspectives presented.

Contextual Notes

Some statements depend on specific definitions of friction types and the conditions of motion (e.g., rolling without sliding). There are also unresolved aspects regarding the conditions under which friction does work and creates torque.

kolua
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can kinetic friction cause a torque? (can it result in rotation)
Or is it that only static friction can cause a torque?

Can static friction do work on a rolling object?
I think it can? because the rotational kinetic energy is increasing? is this right?
HELP!
 
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First question response: Ask your self "what is the result of friction?" and "what does it take to create torque?" and you should see the answer to your question.

Second question response: The answer to the first question should let you know if the second statement is true.
 
kolua said:
can kinetic friction cause a torque? (can it result in rotation)
Or is it that only static friction can cause a torque?
Yes it can: if the line of action of the friction force doesn't go through the center of mass, then that force represents a torque.
Can static friction do work on a rolling object?
I think it can? because the rotational kinetic energy is increasing? is this right?
HELP!
Yes it can: if the object is sliding and rolling you can have what you describe. So in exercises the term "rolling without sliding" may appear to exclude that.

[edit]JBA was faster !
 
Your are right in both of your answers except wrong in your statement about "static" friction applying to sliding while rolling, because that is kinetic friction; which, can also create torque and rotation while sliding.
 
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