$A$ truck of mass $10,000 \ kg$ is moving up an inclined plane with a slope of $1 \ m$ in $50 \ m$. If the speed of the truck is $36 \ km/hr$,find the power of the engine in $kW$. (Take $g = 10 \ m/s^2$)

$A$ quarter horsepower motor runs at a speed of $600 \ rpm$. Assuming $60 \%$ efficiency,the work done by the motor in one rotation is (in $J$)

The average work done by a human heart while it beats once is $0.5 \, J$. Calculate the power used by the heart if it beats $72$ times in a minute.

Why is electrical power required at all when the elevator is descending? Why should there be a limit on the number of passengers in this case?

$A$ man $M_1$ of mass $80 \ kg$ runs up the stairs with a box in $15 \ s$. Another man $M_2$ of the same mass $80 \ kg$ runs up the same stairs with the same box in $20 \ s$. Find the ratio of the power generated by them.

An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of $2\, m/s$. The mass per unit length of water in the pipe is $100\, kg/m$. What is the power of the engine $?$ ................ $W$