Suppose a sphere rolls without slipping on horizontal stationary ground. Now, suppose the sphere rolls onto a surface which is moving at some velocity with respect to the previous stationary ground. How will the velocity of the rolling sphere change ?

As far as I understand, energy will be conserved. But then what ? Rolling friction is negligible and can be neglected, however other forms of friction (sliding friction) may or may not be present.

If it's not clear, what I wish to know is the behaviour of a pure rolling sphere when it moves onto a moving surface from a stationary one.

Thanks in advance.


As soon as the sphere moves to the moving surface, the sphere will experience a torque due to kinetic friction, but this is not pure rolling. The angular velocity of the sphere keeps increasing until it's $r \omega$ (r-radius of sphere, $\omega$-angular velocity) equals the velocity of the moving surface. Once this is reached, it undergoes pure rolling.


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