Question

A ball is dropped from the top of a tower of 100m. Simultaneously another ball is thrown upward from the bottom of the tower with a speed 50m/s . At what time will these two balls cross each other

Answer 1

let it be after t sec.

After t sec. the ball which is dropped from a height of 100m

travels a distance of S1 = 0.5*10*t^2

After t sec. the other ball thrown with a velocity of 50m/s travels

S2 = 50t - 0.5*10*t^2

Now, S1 + S2 = 100m

Or, 5t^2 + 50t- 5t^2 = 100

Or, t = 2 sec