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A thin ring of mass 2kg and radius 0.5m is rolling without slipping on a horizontal plane with velocity 1m/s. A small ball of mass 0.1kg,moving with velocity 20m/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      

a)

The ring has pure rotation about its stationary

b)

The ring comes to a complete stop

c)

Friction between the ring the ground is to the left

d)

There is no friction between the ring and the ground



Question ID - 100601 | SaraNextGen Top Answer

A thin ring of mass 2kg and radius 0.5m is rolling without slipping on a horizontal plane with velocity 1m/s. A small ball of mass 0.1kg,moving with velocity 20m/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      

a)

The ring has pure rotation about its stationary

b)

The ring comes to a complete stop

c)

Friction between the ring the ground is to the left

d)

There is no friction between the ring and the ground

1 Answer
127 votes
Answer Key / Explanation : (a,c) -

(a,c)

The data is incomplete. Let us assume that friction from ground on ring is not impulsive during impact.

From linear momentum conservation in horizontal direction,

we have

Here,  is the velocity of CM of ring after impact.

Solving the above equation, we have

Thus CM becomes stationary.

 Correct answer is (a).

Linear impulse during impact

(i)In horizontal direction

(ii)In vertical direction

Writing the equation (about CM)

Angular impulse = Change in angular momentum

We have

Solving this equation  becomes out ot be positive or  anti-clockwise. So just after collision rightwards slipping is taking place. Hence, friction is leftwards. Therefore, option (c) is also correct.

 Correct options are (a) and (c).

127 votes


127