If the breaking strength of a rope is $\frac{4}{3}$ times the weight of a person, then the maximum acceleration with which the person can safely climb up the rope is ( $\mathrm{g}=$ acceleration due to gravity)

A block of mass 2 kg is placed on a rough horizontal surface. If a horizontal force of 20 N acting on the block produces an acceleration of $7 \mathrm{~ms}^{-2}$ in it, then the coefficient of kinetic friction between the block and the surface is

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

The apparent weight of a girl of mass 30 kg when she is in a lift moving vertically upwards with an acceleration of $2 \mathrm{~ms}^{-2}$ is (Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )

Two bodies $A$ and $B$ of masses 1.5 kg and 3 kg are moving with velocities $20 \mathrm{~ms}^{-1}$ and $15 \mathrm{~ms}^{-1}$ respectively. If the same retarding force is applied on the two bodies, then the ratio of the distances travelled by the bodies $A$ and $B$ before they come to rest is