$A$ stone thrown upward with a speed $u$ from the top of a tower reaches the ground with a velocity $3u$. The height of the tower is (in $u^2/g$)

$A$ ball is dropped from rest at time $t=0$ from a certain height. $A$ second ball is dropped from the same height at time $t=1 \,s$. At what time $t$, does the distance between the two balls become $10 \,m$ (in $s$)?

$A$ ball is projected vertically upward with an initial velocity of $50 \; ms^{-1}$ at $t = 0 \; s$. At $t = 2 \; s$,another ball is projected vertically upward with the same velocity. At $t = \dots \; s$,the second ball will meet the first ball $(g = 10 \; ms^{-2})$.

What will be the ratio of the distance moved by a freely falling body from rest in $4^{th}$ and $5^{th}$ seconds of journey?

Two stones of different masses are dropped simultaneously from the top of a building. Which of the following statements is true regarding their motion?

Free-fall: Discuss the motion of an object under free fall. Neglect air resistance.