It takes $20 \mathrm{s}$ for a person $A$ to climb up the stairs, while another person $B$ does the same in $15 \mathrm{s}$. Compare the (i) Work done and (ii) power developed by the persons $A$ and $B$.

A weight lifter lifts a load of $200 \mathrm{kgf}$ to a height of $2.5 \mathrm{m}$ in $5 \mathrm{s}$. Calculate: (i) the work done, and (ii) the power developed by him. 

A boy of mass $40 \mathrm{kg}$ runs up a flight of $15$ steps each $15 \mathrm{cm}$ high in $10 \mathrm{s}$. Find the power developed by him in watt?

Take $\mathrm{g} = 10 \mathrm{N} {\mathrm{kg}}^{-1}$