A ball is thrown vertically upwards with a speed of `10 m//s` from the top of a tower 200 m height and another is thrown vertically downwards with the same speed simultaneously. The time difference between them on reaching the ground is `(g=10 m//s^(2))`

Options

A. 12
B. 6
C. 2
D. 1

Answer

C

Explanation

As the ball thrown vertically upwards will come back to the point of projection with the same speed , both the balls will move downwards with same initial velocity, so both will hit ground with velocity `v= sqrt(u^(2)+2gh)` . However , the ball projected up will take `(2u)/(g)(=2xx(10)/(10)=2s)` time more to reach the ground than the ball projected downwards.