One stone is projected horizontally from a `20 m` high cliff with an initial speed of `10 ms^(-1)`. A second stone is simultaneously dropped from that cliff. Which of the following is true?

Options

A. Both strike the ground with the same speed.
B. The ball with initial speed `10 " ms"^(-1)` reaches the ground first.
C. Both the balls hit the ground at the same time.
D. None of these

Answer

C

Explanation

`10 "m/s"=u_(A),`
`U_(B)=0" m/s" " " U_(A)= 10 overset ^ i`

On reaching ground,
Both will have vertical vel
`V_(y)^(2)=u_(y)^(2)+2a_(y) S_(y)`
Since `U_(y)` = 0 for both A & B
`a_(y)=g` for both A & B
`S_(y)=20` m for both A & B
Thats why the time taken by both are same