If the height of a projectile at a time of 2 s from the beginning of motion is 60 m , then the time of flight of the projectile is

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

A disc of mass 0.2 kg is kept floating in air without falling by vertically firing bullets each of mass 0.05 kg on the disc at the rate of 10 bullets per every second. If the bullets rebound with the same speed, then the speed of each bullet 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

If a force $\mathbf{F}=(3 \hat{\mathbf{i}}-2 \hat{\mathbf{j}}) \mathrm{N}$ acting on a body displaces it from point $(1 \mathrm{~m}, 2 \mathrm{~m})$ to point $(2 \mathrm{~m}, 0 \mathrm{~m})$, then work done by the force is