A bob of mass $10 \mathrm{g}$ is tied to a string and made to oscillate in a vertical plane. If the bob is displaced by $10°$ with respect to the vertical and the tension in the string is $0.1 \mathrm{N}$, what is the work done by the tension? The string is inextensible.

A body of mass $3 \mathrm{kg}$  is displaced through $\mathrm{s}$ metre in $t$ second by a certain force, where $s=\frac{1}{3}{t}^2$. The work done by the force in $2$ seconds is

A raindrop of radius $R$ fell on the ground from a height $H$ above the ground. The work done by the gravitational force is proportional to

The upper half of an inclined plane with inclination $\varphi$ is perfectly smooth, while the lower half is rough. A body starting from rest at the top will again come to rest at the bottom, if the coefficient of friction for the lower half is given by:

A body of mass m moving with a velocity $v$ collides head on another body of mass $2 \mathrm{m}$ which is initially at rest. The ratio of KE. of the colliding body before and after collision will be

A mass $m$ moves with a velocity $v$ and collides inelastically with another identical mass. After collision, the first mass moves with velocity $\frac{v}{\sqrt{3}}$ in a direction perpendicular to the initial direction of motion. Find the speed of the second mass after the collision.