$A$ body falling from a vertical height of $10 \, m$ pierces through a distance of $1 \, m$ in sand. It faces an average retardation in sand equal to (where $g$ = acceleration due to gravity).

$A$ body is projected vertically upwards with a velocity $u$ from the top of a tower. The time taken by it to reach the ground is $n$ times the time taken by it to reach the highest point in its path. The height of the tower is:

$A$ 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 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 $g = 10 \, m/s^2$]

$A$ stone thrown upward with a speed $u$ from the top of a tower reaches the ground with a velocity $4 u$. The height of the tower is .........

An object is projected upwards with a velocity of $100 \, m/s$. It will strike the ground after (approximately) ........ $sec$.