Rotation - Friction on Rolling Sphere

[cupid.callin]

Homework Statement

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?

 

[Doc Al]

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?

 

[cupid.callin]

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

Sorry for trouble Doc Al