Is rolling resistance related to relative motion at the point of contact?

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Discussion Overview

The discussion revolves around the concept of rolling motion on an inclined plane, specifically focusing on the work done by frictional forces and the relative motion at the point of contact between a rolling object and the surface. Participants explore the implications of rolling without slipping and the nature of rolling resistance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question why the work done by frictional force is considered zero during purely rolling motion, despite the presence of a force and displacement in opposite directions.
  • Others emphasize that work is related to changes in kinetic energy, suggesting that forces affecting only the direction of velocity do not perform work in the traditional sense.
  • There is a query regarding the meaning of relative motion at the point of contact between the object and the ground, with a distinction made between slipping and purely rolling conditions.
  • One participant notes that rolling resistance is attributed to non-elastic deformations at the point of contact, indicating energy loss during rolling.

Areas of Agreement / Disagreement

Participants express differing views on the nature of work done by friction in rolling motion, and there is no consensus on the implications of relative motion at the point of contact. The discussion remains unresolved regarding the significance of these concepts.

Contextual Notes

Participants have not fully explored the assumptions underlying the definitions of work and energy in the context of rolling motion, nor have they resolved the mathematical implications of these concepts.

iitjee10
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When there is purely rolling motion in an inclined plane, it is mentioned that work done by the frictional force is zero!
Why should it be zero as there is definitely a force as well as displacement in opposite direction of force?
Is this true or for rolling motion there is some other significance?

Plzz help
 
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iitjee10 said:
When there is purely rolling motion in an inclined plane, it is mentioned that work done by the frictional force is zero!
Why should it be zero as there is definitely a force as well as displacement in opposite direction of force?
Is this true or for rolling motion there is some other significance?

Plzz help
If the object is purely rolling, i.e. there is no slipping, what can you say about the [relative] velocity of the point of contact on the body and the inclined plane?
 
iitjee10 said:
When there is purely rolling motion in an inclined plane, it is mentioned that work done by the frictional force is zero!
Why should it be zero as there is definitely a force as well as displacement in opposite direction of force?
Is this true or for rolling motion there is some other significance?

Plzz help
Remember that work is directly related to changes in kinetic energy.
Because changes in kinetic energy is related to changes in SPEED, rather than to changes in velocity, it follows that forces that ONLY change the direction of velocitiy (rather than changing its magnitude) do not do any work, in the sense of how work is defined in physics.
 
what does it mean by relative motion between point of contact and ground?
 
iitjee10 said:
what does it mean by relative motion between point of contact and ground?
Should be relative motion at the point of contact with the ground. If the object is slipping, then there is relative motion between the surface of the object and the ground at the point of contact. If the object is purely rolling, then there is zero relative motion between the surface of the object and the ground at the point of contact.

If you're wondering about rolling resistance, it's due to non-elastic (energy lost) deformations at the point of contact.
 

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