$A$ ball is dropped from a bridge of $122.5 \ m$ above a river. After the ball has been falling for $2 \ s$,a second ball is thrown straight down after it. What is the initial velocity of the second ball so that both hit the water at the same time (in $m/s$)?

$A$ man in a balloon rising vertically with an acceleration of $4.9\,m/s^2$ releases a ball $2\,s$ after the balloon is let go from the ground. The greatest height above the ground reached by the ball is...........$m$ $(g = 9.8\,m/s^2)$

Discuss the observation of Galileo for objects falling freely.

When a ball is thrown up vertically with velocity $u,$ it attains a maximum height $H.$ What should be the velocity so that maximum height becomes $2H$?

$Assertion$ : Two balls of different masses are thrown vertically upward with the same speed. They will pass through their point of projection in the downward direction with the same speed.
$Reason$ : The maximum height and downward velocity attained at the point of projection are independent of the mass of the ball.

$A$ ball is released from the top of a tower of height $H \ m$. It takes $T \ s$ to reach the ground. The height of the ball from the ground after $\frac{T}{4} \ s$ is