$A$ body falling freely under gravity passes two points $30 \ m$ apart in $1 \ s$. From what point above the upper point did it begin to fall? (Take $g = 10 \ m \ s^{-2}$)

$A$ ball is thrown vertically upwards with a velocity of $15 \ m/s$. To what maximum height will it reach? (Take $g = 10 \ m/s^2$)

$A$ ball is thrown vertically upwards from the top of a tower with a velocity $u$. This ball reaches the ground level with a velocity $4u$. The height of the tower is:

$A$ stone is dropped from a height $h$. It hits the ground with a certain momentum $P$. If the same stone is dropped from a height $100\%$ more than the previous height,the momentum when it hits the ground will change by ........... $\%$.

Two balls of the same size,but where the density of one is greater than that of the other,are dropped from the same height. Which ball will reach the Earth first (air resistance is negligible)?

$Assertion$ : Two balls of different masses are thrown vertically upward with the same speed. They will pass through their point of projection in the downward direction with the same speed.
$Reason$ : The maximum height and downward velocity attained at the point of projection are independent of the mass of the ball.