$A$ ball is dropped from a height $h$ above the ground. Neglecting air resistance,its velocity $(v)$ varies with its height $(y)$ above the ground as:

If a freely falling body travels in the last second a distance equal to the distance travelled by it in the first three seconds,the time of the travel is ........ $sec$.

$A$ stone is dropped from the top of a building. When it crosses a point $5 \, m$ below the top,another stone starts to fall from a point $25 \, m$ below the top. Both stones reach the bottom of the building simultaneously. The height of the building is ..... $m$.

$A$ stone falls from a balloon that is descending at a uniform rate of $12 \, m/s$. The displacement of the stone from the point of release after $10 \, s$ is.......$m$ $(g = 9.8 \, m/s^2)$

$A$ 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 . . . . . . $m$. $(g = 10 \ m/s^2)$

Two balls $A$ and $B$ are thrown with the same velocity $u$ from the top of a tower. Ball $A$ is thrown vertically upwards and ball $B$ is thrown vertically downwards. If $t_A = 6 \ s$ and $t_B = 2 \ s$,then the velocity $u$ of each ball is ....... $m/s$.