A thin ring of mass 2 kg and radius 0.5 m is rolling without on a horizontal plane with velocity 1 m/s. A small ball of mass 0.1 kg, moving with velocity 20 m/s in the opposite direction, hits the ring at a height of 0.75 m and goes vertically up with velocity 10 m/s. Immediately after the collision: [2011]

Question

Smart Achievers · Accepted Answer

(3)

The angular impulse created by the frictional force between the ring and the ball tends to decrease the angular speed $ω$ of the ring about O.

After the collision $ω$ decreases but the ring remains rotating in the anticlockwise direction. Hence the friction between the ring and the ground at the point of contact is to the left.

Solution

1 the ring has pure rotation about its stationary CM.

2 the ring comes to a complete stop.

3 friction between the ring and the ground is to the left.

4 there is no friction between the ring and the ground.

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