Two balls of mass $M$ and $2 \,M$ are thrown horizontally with the same initial velocity $v_{0}$ from top of a tall tower and experience a drag force of $-k v(k > 0)$, where $v$ is the instantaneous velocity. then,

A body is projected horizontally from a height with speed $20$ metres/sec. ........ $metres/sec$ will be its speed after $5$ seconds ($g = 10\,\,metres/{\sec ^2})$

A wheel of radius $r$ rolls without slipping with a speed $v$ on a horizontal road. When it is at a point $A$ on the road, a small jump of mud separates from the wheel at its highest point $B$ and drops at point $C$ on the road. The distance $AC$ will be

A ball rolls from the top of a stair way with a horizontal velocity $u\; m /s$ . If the steps are $h\; m$ high and $b\; m$ wide, the ball will hit the edge of the $n^{th}$ step, if $n=$

A child stands on the edge of the cliff $10\,m$ above the ground and throws a stone horizontally with an initial speed of $5\,ms ^{-1}$. Neglecting the air resistance, the speed with which the stone hits the ground will be $..........ms ^{-1}$ (given, $g =10\,ms ^{-2}$)

A ball rolls off the top of a stairway with horizontal velocity $\mathrm{u}$. The steps are $0.1 \mathrm{~m}$ high and $0.1 \mathrm{~m}$ wide. The minimum velocity $\mathrm{u}$ with which that ball just hits the step $5$ of the stairway will be $\sqrt{\mathrm{x}} \mathrm{ms}^{-1}$ where $\mathrm{x}=$___________ [use $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$ ].