$A$ ball is thrown upward from the ground with an initial speed of $v$. At the same instant, another ball is dropped from a building of height $20 \,m$. If the balls are at the same height after $0.8 \,s$, then the magnitude of $v$ is (Take, acceleration due to gravity $=10 \,ms^{-2}$) (in $\,ms^{-1}$)

An object is projected upwards with a velocity of $100 \, m/s$. It will strike the ground after (approximately) ........ $sec$.

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

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 a ball $C$ is thrown with the same velocity $u$ in the horizontal direction from the top of the tower,and if $t_A = 6 \ s$ and $t_B = 2 \ s$,then the time $t_C$ taken by ball $C$ to reach the ground is equal to........$s$.

$A$ ball is released from the top of a tower of height $H \ m$. It takes $T \ s$ to reach the ground. The height of the ball from the ground after $\frac{T}{4} \ s$ is

$A$ body is dropped from a tower of height $h$. It reaches the ground at $t = 4\, s$. What is the height of the tower in $m$?