Two tal buldings are situated ` 200 m` apart, With what speed muat a ballbe thrown horixontally fromt eh winow ` 550` m above the ground in one building so that it will enter a window ` 50 m` above the ground in the other building ? Take ` g= 10 ms^(-2)`.

Explanation

Vertcal distanace to be travelled by ball,
` y= 550 - 50 = 500 m`
Horizontal distance to be ravelled by ball,
` x = 200 m`
Let (u) be the horizontal velocity of projection of ball and it reaches in time (t) in the other building.
` Then, ` y = 1/2 gt^2`
or ` t= sqrt (2 y)/g = sqrt ( 2 xx 500) /(10) = 10 s`
Now ` x=ut ` or 200 =u xx 10 or ` u = 20 ms^(-1)`.