The average power generated by a 90 kg mountain climber who climbs a summit of height 600 m in 90 min is (Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )

A light body of momentum $p_L$ and a heavy body of momentum $p_H$ both have the same kinetic energy, then

A machine with efficiency $\frac{2}{3}$ used 12 J of energy in lifting 2 kg block through certain height and it is allowed to fall through the same. The velocity while it reach the ground is