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

$A$ body is projected upwards with a speed $u$ and the time taken by it to reach the maximum height $H$ is $T$. Pick out the correct statement.

$A$ ball is dropped from a bridge $122.5\, m$ above a river. After the ball has been falling for $2\, s$,a second ball is thrown straight down after it. What must its initial velocity be so that both hit the water at the same time?.......$m/s$

$A$ particle is dropped under gravity from rest from a height $h$ $(g = 9.8 \ m/s^2)$. If it travels a distance of $9h/25$ in the last second of its motion,the height $h$ is ......... $m$.

If the water falls from a dam into a turbine wheel $19.6 \ m$ below,then the velocity of water at the turbines is .................. $m/s$ (take $g = 9.8 \ m/s^2$).

$A$ 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 ..... $m$.