Question:
How is the power related to the speed at which a body can be lifted? How many kilograms will a man working at the power of $100 \mathrm{~W}$, be able to lift at constant speed of $1 \mathrm{~ms}^{-1}$ vertically ? $\left(\mathrm{g}=10 \mathrm{~ms}^{-2}\right)$
Solution:
$\mathrm{P}=\mathrm{Fu}=m g u$
$\therefore m=\frac{P}{g v}=\frac{100}{10 \times 1}=10 \mathrm{~kg} .$