A solid sphere rolling on a rough horizontal surface with a linear speed u collides elastically with a fixed, smooth, vertical wall, Find the speed of the sphere after it has started pure rolling in the backward direction.

Given:
Linear speed= u
Let the solid sphere collides with the wall and its velocity after collision is v towards left.
Angular momentum of the sphere= ![]()
After collision, it rebounds and starts rolling. Now, let the velocity of the sphere be v’ and the angular velocity be ![]()
Therefore, angular momentum of the sphere = ![]()
Using both the equations
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