Question

2 buildings are situated 200m apart. With what speed must ball be thrown horizontally from the window 540 m above the ground in one building, so that it will enter a window 50 metre above the ground in the other?

Answer 1

this question is based on concept of horizontal projectile .
use trajectory equation of Horizontal projectile.

e.g Y = gx²/2u²

where Y is the displacement of object in y-component wrt to frame , x is the displacement of object in x -component wrt frame . g is acceleration due to gravity and u is intial velocity.

here ,
Y = 200 m
x = 540 -50 = 490 m

now,

200 = 10 (490)²/2u²

40 = (490)²/u²

u² = (490)²/40

u = 490/2√10
=77.47 m/s