Two tall buildings are 40 m apart. With what speed must a ball be thrown horizontally from a window 145 m above the ground in one building, so that it will enter a window 22 . 5 m above from the ground in the other?

Step-by-step solution

Given, u x = v and u y = 0 Separating the motion in x and y directions Using x = u x t + 1 2 a t 2 40 = v t (i) ⟹ t = 40 v (ii) y  =  h net = 145 - 22.5 Using y = u y t + 1 2 a t 2 122.5 = 0 + 1 2 × 10 t 2 122.5 = 5 40 v 2 v = 40 5 122.5 = 8   m   s - 1