Two identical balls of equal masses A and B, are lying on a smooth surface as shown in the figure. Ball A hits the ball B (which is at rest) with a velocity `v=16ms^-1`. What should be the minimum value of coefficient of restitution `e` between A and B so that B just reaches the highest point of inclined plane? `(g=10ms^-2)`

Options

A. (a) `2/3`
B. (b) `1/4`
C. (c) `1/2`
D. (d) `1/3`

Answer

B

Explanation

Velocity of B after collision will become,
`((1+e)/(2))v=((1+e)/(2))(16)`
or `8(1+e)m//s`
Now, `8(1+e)=sqrt(2gh)`
`=sqrt(2xx10xx5)=10`
`:. e=0.25`