Time taken by an object falling from rest to cover the height of $h_1$ and $h_2$ is respectively $t_1$ and $t_2$,then the ratio of $t_1$ to $t_2$ is:

$A$ body falling from rest has a velocity $v$ after it falls through a height $h$. The distance it has to fall down further for its velocity to become double,will be $...............\,h$.

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 $2H$?

$A$ balloon starts rising from the ground from rest with an upward acceleration of $2 \, m/s^2$. Just after $1 \, s$,a stone is dropped from it. The time taken by the stone to strike the ground is nearly ....... $s$.

$A$ body dropped from a height $h$ with an initial speed zero,strikes the ground with a velocity $3 \ km/h$. Another body of the same mass is dropped from the same height $h$ with an initial speed of $4 \ km/h$. Find the final velocity of the second body with which it strikes the ground in $km/h$.

If a ball projected vertically upwards with a certain initial velocity from the ground crosses a point at a height of $25 \ m$ twice in a time interval of $4 \ s$,then the initial velocity of the ball is (Acceleration due to gravity $= 10 \ m \ s^{-2}$) (in $m \ s^{-1}$)