Friction on on circular objects while rolling?

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Discussion Overview

The discussion revolves around the role of friction in the motion of circular objects while rolling, particularly addressing why a rolling wheel eventually comes to a stop despite friction seemingly aiding its forward motion. The scope includes theoretical considerations of friction types and their effects on rolling motion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why a rolling wheel stops if friction is helping it move forward, suggesting a misunderstanding of friction's role.
  • Another participant clarifies that friction helps the wheel roll but does not aid in its forward motion, asserting that without friction, the wheel would slip rather than roll.
  • A different viewpoint states that if friction were removed, conservation laws would allow the ball to continue moving without slowing down, indicating that friction's role is primarily to enforce the rolling condition initially.
  • Another participant introduces the concept of rolling resistance, explaining that it opposes relative motion due to deformation at the contact point, and distinguishes between static and kinetic friction in this context.

Areas of Agreement / Disagreement

Participants express differing views on the role of friction in rolling motion, with no consensus reached on whether friction aids forward motion or merely facilitates rolling. The discussion remains unresolved regarding the implications of friction on the stopping of rolling objects.

Contextual Notes

Participants mention various types of friction (static, kinetic, rolling resistance) and their effects, but the discussion does not resolve the complexities of these definitions or their implications for rolling motion.

prashantjha
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friction on on circular objects while rolling??

i had a doubt about circular rolling objects..
it is true that friction opposes relative motion..but while doing so in a rolling wheel rolling forward,the friction also works in forward direction.so then my question is why does the wheel stops after a particular time.if friction is helping it move,then it should move till infinity if left undisturbed??
 
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friction is not helping it move, friction is helping it roll. without friction, the ball is unable to roll at all and will just slip down the slope.

also, the friction on the ball is not in the direction of movement but in the opposite direction, it is the friction on the ramp by the ball that is in the ball's direction of movement. so the friction on the ball is still going in the opposite direction and eventually stops the ball.
 


Friction is not helping it roll in any sense. If you magically removed friction halfway through the experiment, conservation of angular and linear momentum would mean the ball continues in exactly the same way as before (with the exception that it never slows down).

Friction initially influences the rolling motion by enforcing the non-slip condition v = rw. After this, it doesn't do anything but slow the ball down.
 


prashantjha said:
i had a doubt about circular rolling objects..
it is true that friction opposes relative motion
Rolling resistance opposes relative motion. This is due to the losses in deformation (compression) and restoration (expansion back to original shape) of the surfaces at and near the contact point.

Static friction opposes external forces.

Kinetic (sliding) friction opposes relative motion between surfaces, but in this case, an object is not truly rolling any more.
 

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