A balloon with mass ' $m$ ' is descending vertically with an acceleration ' $a$ ' (where $a

A conveyor belt is moving horizontally with a velocity of $2 \mathrm{~ms}^{-1}$. If a body of mass 10 kg is kept on it, then the distance travelled by the body before coming to rest is

(The coefficient of kinetic friction between the belt and the body is 0.2 and acceleration due to gravity is $10 \mathrm{~ms}^{-2}$ )

Two bodies $A$ and $B$ of masses 20 kg and 5 kg respectively are at rest. Due to the action of a force of 40 N separately, if the two bodies acquire equal kinetic energies in times $t_A$ and $t_B$ respectively, then $t_A: t_B=$

A crane of efficiency $80 \%$ is used to lift 8000 kg of coal from a mine of depth 108 m . If the time taken by the crane to lift the coal is one hour, then the power of the crane (in kW ) is

(Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )