A crane lifts a mass of 100 kg to a height of 10 m in 20 s. The power of the crane is $(\mathrm{Take} \mathrm{g}=10 {\mathrm{ms}}^{-2}\mathrm{ ) }$

Here, $\mathrm{m}=100 \mathrm{kg}, \mathrm{h}=10 \mathrm{m}, \mathrm{t}=20 \mathrm{s}$ and  $\mathrm{g}=10 {\mathrm{ms}}^{-2}$
The power of the crane is 
$\therefore \mathrm{P}=\frac{\mathrm{mgh}}{\mathrm{t}}=\frac{\left(100\mathrm{kg}\right)\left(10{\mathrm{ms}}^{-2}\right)\left(10\mathrm{m}\right)}{\left(20\mathrm{s}\right)}=500 \mathrm{W}$