Question

On a smooth carrom board. A coin located at `(4,6)` is moving in negative `y-`direction with speed `3m//s` is being hit at that point by a striker moving along negative `x-` axis . The line joining centre of the coin and striker just before the collision is parallel to `x-` axis. After collision the coin goes into the hole located at origin. Mass of the striker and the coin is equal. Considering the collision to be elastic, find the velocity `(` in vector form `)` of the stricker before the collision and after the collision.

Answer 1

Correct Answer - `(2,0)`
The line of impact for duration of collision is parallel to `x-` axis .
The situation of striker and coin just before the collision is given as

Because masses of coin and striker are same, their components of velocities along line of impac shall exchange. Hence the striker comes to rest and the `x-y` component of velocities of coin are `u` and 3 as shown in figure.

For coin to enter hole,
its velocity must be along `PO`
`:. tan theta=(6)/(4)=(3)/(4)`
or `u=2m//s Ans. (2,0)`