Two identical balls `A` and `B` are released from the position shown in Fig. They collide elastically with each other on the horizontal portion. The ratio of heights attained by `A` and `B` after collision is (neglect friction)

Options

A. `1 : 4`
B. `2 : 1`
C. `4 : 13`
D. `2 : 5`

Answer

`(3)`

Explanation

`u_(B) = sqrt(2gh) , u_(A) = sqrt(8gh)`
`h_(A) = (V_(A)^(2))/(2g) = h, h_(B) = h + (V_(B)^(2) sin ^(2) 60)/(2g)`
(As velocity are exchanged, `V_(A) = u_(B) & V_(B) = u_(A)`)