An engine develops $20 kW$ of power. How much time will it take to lift a mass of $200 kg$ to a height of $40 m$ (in $s$)? $(g=10 m s^{-2})$

Calculate the power of a crane in watts,which lifts a mass of $100 \, kg$ to a height of $10 \, m$ in $20 \, s$. (in $, W$)

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

The force acting on a particle moving in a straight line varies with the velocity of the particle as $F = \frac{K}{v}$,where $K$ is a constant. The work done by this force in time $t$ is

$A$ man of mass $50 \ kg$ carries an object to a height of $20 \ m$ in a time of $10 \ s$. The power used by the man in this process is $2000 \ W$. Find the mass of the object carried by the man (take $g = 10 \ m/s^2$). (in $kg$)

$A$ quarter horsepower motor runs at a speed of $600 \text{ r.p.m.}$ Assuming $40\%$ efficiency,the work done by the motor in one rotation will be: