A man throws balls with the same speed vertically upwards one after the other at an interval of 2s. What should be the speed of the throw so that more than two balls are in the sky at any time ? (Given `g = 9.8 m//s^(2)`)

Answer

A, B

Explanation

As given horizontal velocity `=40 m//s`
`u cos theta xxt=40, t=1` sec
at `t=1`, height `=50 m`
`:. 50=u sin theta xx1-1//2xxgxx1rArr u sin theta=55`
`:.` Initial vertical component `=u sin theta=55 m//s`
As hoop is on same height of the trajectory. So by symmetry x will be 40 m.