Average Power

Average power is the rate at which work is done, defined as $P_{avg}=W/t$, where the work done against gravity to lift the water equals its gain in gravitational potential energy. Lifting the water at steady speed requires work $W=mgh$, after which dividing by elapsed time gives the power. Taking $g=10{\text{ m/s}}^2$, the work is $W=300\times 10\times 10=30000\text{ J}$. Dividing by the time, $P_{avg}=30000/60=500\text{ W}$. The option 300 W ignores the height factor and divides incorrectly. The option 5000 W omits the division by time entirely, reporting the work scaled wrongly. The option 50 W underestimates by an order of magnitude through a misplaced decimal. This is the NCERT definition of average power as work per unit time. As a unit check, joules divided by seconds gives watts, and a half-kilowatt pump for this modest lifting task is physically reasonable.