A smooth sphere A is moving on a frictionless horizontal plane with angular speed `omega` and centre of mass velocity `upsilon`. It collides elastically and head on with an identical sphere B at rest. Neglect friction everywhere. After the collision, their angular speeds are `omega_A and omega_B` respectively. Then

Options

A. `omega_(A)ltomega_(B)`
B. `omega_(A)=omega_(B)`
C. `omega_(A)=omega`
D. `omega_(B)=omega`

Answer

C

Explanation

Since the spheres are smooth, there will be no transfer of angular momentum from the sphere A to sphere B. The sphere A only transfer its linear velocity v to the sphere B and will continue to rotate with the same angular speed `omega`.