An electric motor produces a tension of $4500 N$ in a wire and the reel winds at a rate of $2 ms^{-1}$. What is the power of the electric motor?

$A$ $60 \ kg$ man runs up a staircase in $12 \ s$ while a $50 \ kg$ man runs up the same staircase in $11 \ s$. The ratio of the rate of doing their work is:

If the maximum load carried by an elevator is $1400\,kg$ ($600\,kg$ passenger $+ 800\,kg$ elevator),which is moving up with a uniform speed of $3\,m/s$ and the frictional force acting on it is $2000\,N$,then the maximum power used by the motor is $...........\,kW$ (take $g = 10\,m/s^2$).

$A$ pump on the ground floor of a building can pump up water to fill a tank of volume $30 \; m^{3}$ in $15 \; min$. If the tank is $40 \; m$ above the ground, and the efficiency of the pump is $30 \%$, how much electric power (in $kW$) is consumed by the pump?

$A$ vehicle of mass $m$ starts from rest and accelerates. If the engine delivers a constant power $p$,what is the velocity of the vehicle at time $t$?

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 $, W$)