The power of a crane, which lifts a mass of $1000 \text{ kg}$ to a height of $20 \text{ m}$ in $10 \text{ s}$ is: $(g = 9.8 \text{ ms}^{-2})$

$A$ body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time $t$ is proportional to

$A$ $750 \,W$ motor drives a pump which lifts $300 \,L$ of water per minute to a height of $6 \,m$. The efficiency of the motor is nearly (Take,acceleration due to gravity to be $10 \,m/s^2$) (in $\%$)

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

An elevator can carry a maximum load of $1800 \; kg$ (elevator $+$ passengers) and is moving up with a constant speed of $2 \; m s^{-1}$. The frictional force opposing the motion is $4000 \; N$. Determine the minimum power delivered by the motor to the elevator in watts as well as in horsepower.

$A$ body of mass $m$ starts from rest and acquires a velocity $v$ in time $t$ under the action of a constant force $F$. The instantaneous power delivered to the body at time $t$ is: