Two balls are thrown simultaneously,A vertically upward with speed 20m/s from the ground and B vertically downward from a height of 40m with same speed and along the same line motion. At which point ball will collide ??

Answers (1)
S safeer

X be the distance from the ground where the collision takes place then

Distance from top of tower up to the collision point =40-X

let collision took place after time t then

X=20t-1/2×g×t^2……(1)(upward motion)

40-X=20t+1/2g×t^2….(2)(downward motion)

Adding (1) and (2) we get


Which gives t=1 second

Putting value of t in (1) we get

 ( taking :g= 9.8 m /s^2)

X=15.1 metre

So collision takes at 15.1 metres from ground or 40–15.1=24.9 metres from top.