$A$ body projected vertically upwards with a velocity $u$ returns to the starting point in $4 \, s$. If $g = 10 \, m/s^2$,the value of $u$ is $......... \, m/s$.

When a ball is thrown up vertically with velocity $V_o$,it reaches a maximum height of $h$. If one wishes to triple the maximum height,then the ball should be thrown with what velocity?

$A$ body is dropped from a certain height $h$ ($h$ is very large) and a second body is thrown downward with a velocity of $5 \, m/s$ simultaneously. What will be the difference in the heights of the two bodies after $3 \, s$?

$A$ ball dropped from the top of a tower falls the first half of the height of the tower in $10 \, s$. The total time spent by the ball in the air is ......... $s$. [Take $g = 10 \, m/s^2$]

$A$ particle is projected vertically upwards such that it attains a height of $h$ after $5 \ s$ and $9 \ s$ of its motion. The speed of projection is $...... \ m/s$ $(g = 10 \ m/s^2)$.

$A$ ball is projected upwards. Its acceleration at the highest point is