A tennis ball is dropped on to the floor from a height of $9.8\,m$. It rebounds to a height $5.0\,m$. Ball comes in contact with the floor for $0.2\,s$. The average acceleration during contact is $……….ms ^{-2}$. [Given $g =10\,ms ^{-2}$ ]

A ball is dropped from a bridge of $122.5$ metre above a river. After the ball has been falling for two seconds, a second ball is thrown straight down after it. Initial velocity of second ball so that both hit the water at the same time is …… $m / s$

A particle is projected vertically upwards from a point $A$ on the ground. It takes time $t_1$ to  reach a point $B$, but it still continues to move up. If it takes further $t_2$ time to reach the  ground from point $B$. Then height of point $B$ from the ground is-

A particle is released from rest from a tower of height $3\, h$. The ratio of times to fall  equal heights $h$, i.e., $t_1 : t_2 : t_3$ is

From a building two balls $A$ and $B$ are thrown such that $A$ is thrown upwards and $B$ downwards with the same speed (both vertically). If $v_{A}$ and $v_{B}$ are their respective velocities on reaching the ground then,