JEE Advanced2011PhysicsCenter of Mass, Momentum and CollisionActual
A thin ring of mass 2 ~kg and radius 0.5 ~m is rolling without slipping 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 directions, hits the ring at a height of 0.75 ~m and goes vertically up with velocity 10 m / s . Immediately after the collision
Options
- Athe ring has pure rotation about its stationary CM
- Bthe ring comes to a complete stop
- Cfriction between the ring and the ground is to the left
- Dthere is no friction between the ring and the ground
Correct answer
A. the ring has pure rotation about its stationary CM
Step-by-step solution
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 aligned & (-2 1)+(0.1 20) & =(0.1 0)+(2 v) -ve +v e aligned Here, v is the velocity of CM of ring after impact. Solving the above equation, we have v=0 Thus, CM becomes stationary. Correct answer is (a). Linear impulse during impact (i) In horizontal direction J₁= P=0.1 20=2 Ns (ii) In vertical direction J₂= P=0.1 10=1 Ns Writing the equation (abo