A very large number of balls are thrown vertically upwards in quick successions in such a way that the next ball is thrown when the previous one is at the maximum height. If the maximum height is 5m, then number of balls thrown per minute is (take `g=10m//s^(2)`)

Options

A. 120
B. 80
C. 60
D. 40

Answer

C

Explanation

`H_(max) = 5`
`H_(max) = (u^2)/(2g) rArr u = sqrt(2 xx 10 xx 5) = 10 m//s`
Time interval between two balls
`t = u/g = 10/10 = 1sec = 1/60 `min
Number of ball thrown per min. = 60.