Two spheres of same size,one of mass $2\, kg$ and another of mass $4\, kg$,are dropped simultaneously from the top of Qutab Minar (height $= 72\, m$). When they are $1\, m$ above the ground,the two spheres have the same

$A$ man in a balloon rising vertically with an acceleration of $4.9\,m/s^2$ releases a ball $2\,s$ after the balloon is let go from the ground. The greatest height above the ground reached by the ball is...........$m$ $(g = 9.8\,m/s^2)$

$A$ man throws balls with the same speed vertically upwards one after the other at an interval of $2\,s$. What should be the speed of the throw so that more than two balls are in the sky at any time? (Given $g = 9.8\,m/s^2$)

$A$ diving board is at a height of $h$ from the water surface. $A$ swimmer standing on this board throws a stone vertically upward with a velocity of $16 \,ms^{-1}$. It reaches the water surface in a time of $5 \,s$. In the next $0.2 \,s$, the diver hears the sound from the water surface. What is the speed of sound (in $\,ms^{-1}$)? (Take acceleration due to gravity $g=10 \,ms^{-2}$)

$A$ window is $50\,cm$ long. $A$ stone is falling from a height of $40\,cm$ above the window. It crosses the window in

$A$ particle is thrown vertically upwards. It passes the same height at $t_1 = 2 \; s$ and $t_2 = 10 \; s$. The height is: