$A$ force of $(2\hat{i} + 3\hat{j} + 4\hat{k})\,N$ acts on a body for $4\,s$ and produces a displacement of $(3\hat{i} + 4\hat{j} + 5\hat{k})\,m$. The power used is :- ............... $W$ (in $.5$)

The force required to row a boat at constant velocity is proportional to the square of its speed. If a speed of $v \, km/h$ requires $4 \, kW$ of power,how much power does a speed of $2v \, km/h$ require?

$A$ pump on the ground floor can pump up water to fill a tank of volume $30 \ m^3$ in $15 \ minutes$. If the tank is $40 \ m$ above the ground and the efficiency of the pump is $30\%$,then the electric power consumed by the pump is ....... $kW$.

An engine pumps water continuously through a hose. Water leaves the hose with a velocity $v$ and $m$ is the mass per unit length of the water jet. What is the rate at which kinetic energy is imparted to water?

$A$ pump draws water from a tank which is $2.5\; m$ below the outlet and discharges it through a hose. The cross-sectional area of the hose is $10\; cm^{2}$,and the water leaves the end of the hose at a speed of $5\; m/s$. What is the power at which the pump is working (in $; W$)? (Assume $g = 10\; m/s^{2}$)

The velocity $v$ reached by a car of mass $m$ at a certain distance from the starting point, driven with constant power $P$, is such that: