Question

A girl of mass $40kg$ climbs $50$ stairs each of average height $20cm$ in $50s$. Find the power of the girl $(g=10m{s}^{-2})$.

• A. $50W$
• B. $50\times 20W$
• C. $80W$
• D. $50\times 20\times 2W$

Answer 1

The correct option is C $80W$

Power $=\frac{workdone}{time}$

$=\frac{changeinPE}{time}=\frac{40\times 10\times 50\times 20\times {10}^{-2}}{50}=80W$