$A$ boy standing at the top of a tower of $20 \, m$ height drops a stone. Assuming $g = 10 \, m/s^2$,the velocity with which it hits the ground is ......... $m/s$.

From $18 \text{ m}$ height above the ground, a ball is dropped from rest. The height above the ground at which the magnitude of velocity equals the magnitude of acceleration (in the same set of units) due to gravity is . . . . . . $\text{m}$. (Take $g = 10 \text{ m/s}^2$ and neglect the air resistance)

$A$ stone is thrown upwards with a velocity $50 \,ms^{-1}$. Another stone is simultaneously thrown downwards from the same location with a velocity $50 \,ms^{-1}$. When the first stone is at the highest point, the velocity of the second stone is $...... \,ms^{-1}$ (Take $g = 10 \,ms^{-2}$).

Which of the following statements is correct?

$A$ boy throws balls into the air at a regular interval of $2 \, s$. The next ball is thrown when the velocity of the first ball is zero. How high does the ball rise above his hand (in $, m$)? [Take $g = 9.8 \, m/s^2$]

$A$ body freely falling from rest has a velocity $v$ after it falls through a height $h$. The total distance it has to fall down from the starting point for its velocity to become double is: (in $h$)