Rotation - Friction on Rolling Sphere

AI Thread Summary
The discussion centers on the role of friction in a rolling sphere, specifically addressing why friction is present even when the lowest point of the sphere has zero velocity. It emphasizes that static friction is necessary to prevent slipping and to provide the torque needed for the sphere to roll without slipping as it accelerates down a slope. Participants express a realization of the concept's simplicity and some frustration with their initial confusion. The importance of friction in maintaining the rolling motion of the sphere is clearly established. Understanding this principle is crucial for solving related physics problems.
cupid.callin
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Homework Statement


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The Attempt at a Solution



The sphere is rolling without sipping, so the lowermost point has 0 velocity ... so why would there be any friction?

I know that if there will be no friction .. sphere will just slide down and not roll but still as i said ... why will there be any friction?
 

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cupid.callin said:
The sphere is rolling without sipping, so the lowermost point has 0 velocity ... so why would there be any friction?
There will be static friction acting at the lowest point. Friction acts to prevent slipping between surfaces--which is exactly what it's doing here. Without friction providing a torque about the center of mass, how could the sphere continue to roll without slipping as it accelerates down the slope?
 
Doc Al said:
There will be static friction acting at the lowest point. Friction acts to prevent slipping between surfaces--which is exactly what it's doing here. Without friction providing a torque about the center of mass, how could the sphere continue to roll without slipping as it accelerates down the slope?

OMG! This was simple ...

I feel like becoming stupider day by day :redface:

Sorry for trouble Doc Al :-p
 

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