$A$ stone is shot straight upward with a speed of $20\, m/s$ from a tower $200\, m$ high. The speed with which it strikes the ground is approximately........$m/s$.

$A$ 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 $...............\,h$.

$A$ paratrooper jumps from an aeroplane and opens a parachute after $2 \ s$ of free fall and starts decelerating with $3 \ m/s^2$. At $10 \ m$ height from the ground, while descending with the help of the parachute, the speed of the paratrooper is $5 \ m/s$. The initial height of the aeroplane is . . . . . . $m$. $(g = 10 \ m/s^2)$

The ratio of the displacements of a freely falling body during the second and fifth seconds of its motion is

$A$ man is standing on top of a building $100\, m$ high. He throws two balls vertically,one at $t = 0$ and the other after a time interval $\Delta t$ (less than $2\, s$). The second ball is thrown at a velocity half that of the first. The vertical gap between the first and second ball is $15\, m$ at $t = 2\, s$. The gap is found to remain constant. Calculate the velocity with which the balls were thrown and the exact time interval between their throws.

$A$ ball is thrown vertically up (taken as $+z-$ axis) from the ground. The correct momentum-height $(p-h)$ diagram is