NUMERICAL QUESTION BASED ON THE MOTION UNDER GRAVITY

Let downward direction be negative and upward direciton be positive.

Say the stones meet at a point that is at a height x above the ground. Let them meet in t seconds.

for stone dropped

u =0; h = -(200-x) m

-(200-x) = 0 + 1/2(-10)t^2

For stone thrown up

u = 40m/s; h = x

x = 40t +1/2(-10)t^2

Then solve for x and t