$A$ 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:

$A$ ball of mass $0.5 \; kg$ is dropped from a height of $10 \; m$. The height from the ground,at which the magnitude of velocity becomes equal to the magnitude of acceleration due to gravity,is $\dots \; m$. (Use $g = 10 \; m/s^2$).

Two balls are released from the same position at a height of $500 \ m$ above the ground, one after the other, with an interval of $1 \ s$. What is the distance between the two balls when the first ball hits the ground (in $m$)? (Acceleration due to gravity $g = 10 \ m/s^2$)

An iron ball and a wooden ball of the same radius are released from a height $h$ in vacuum. The time taken by both of them to reach the ground is equal based on:

$A$ $0.4\,kg$ mass takes $8\,s$ to reach the ground when dropped from a certain height $P$ above the surface of the Earth. The loss of potential energy in the last second of the fall is $..............J$. [Take $g = 10\,m/s^2$]

$A$ juggler maintains four balls in vertically upward motion. He throws the next ball every $1/4 \, s$. For the show to continue,what should be the height to which he throws each ball? (Assume $g = 10 \, m/s^2$)