A boy in a open trucj throws a ball at `40 m//s` at angle `60^(@)` form horizontal. The truck is moving with constant speed `10 m//s` and the boy just after throw, jumps off the truck and starts running in same direction to catch the ball. (Assume same horizontal level)

Options

A. Speed of the boy must be `10 m//s`
B. Speed of the boy must be `30 m//s`
C. Time of flight is `4 sqrt3 s`
D. Distance at which the boy catch the ball from throwing position is `120 sqrt3 m`

Answer

B, C, D

Explanation

`u_(x) = 40 cos 60^(@) + 10 = 30 m//s`
`T = (2u_(j))/(g) = 2 xx (40 xx sqrt(3//2))/(10) rArr 4sqrt3s`
`R = u_(x) xx T`
`= 30 xx 4sqrt3 = 120 sqrt3 m`