When a ball is dropped into a lake from a height $4.9 \,m$ above the water level, it hits the water with a velocity $v$ and then sinks to the bottom with the constant velocity $v$. It reaches the bottom of the lake $4.0,s$ after it is dropped. The approximate depth of the lake is ………… $m$

Two balls of same size but the density of one is greater than that of the other are dropped from the same height, then which ball will reach the earth first (air resistance is negligible)

A body $A$ is projected upwards with a velocity of $98\,m/s$. The second body $B$ is projected upwards with the same initial velocity but after $4 \,sec$. Both the bodies will meet after………..$sec$

A body falls freely from the top of a tower. It covers $36\%$ of the total height in the last second before striking the ground level. The height of the tower is……..$m$

A particle is projected vertically upwards from a point $A$ on the ground. It takes time $t_1$ to  reach a point $B$, but it still continues to move up. If it takes further $t_2$ time to reach the  ground from point $B$. Then height of point $B$ from the ground is-