The work done in increasing the diameter of a soap bubble from 2 cm to 4 cm is (Surface tension of soap solution $=3.5 \times 10^{-2} \mathrm{Nm}^{-1}$ )

An engine is dragging a mass of 5000 kg with a velocity of $5 \mathrm{~ms}^{-1}$ along a smooth inclined plane of inclination 1 in 50 . Then the power of the engine is

A body is moved along a straight line by an engine which delivers a constant power. The distance moved by the body in time $t$ is proportional to

A body of mass 3 kg is moving under the action of a force which causes a displacement of $\left(t^3 / 3\right) \mathrm{m}$, where $t$ is time in seconds. The work done by the force in first 2 sec is