Question

A boy whose mass is $30\text{kg}$ climbs with a constant speed on a vertical rope of $6\text{m}$ length in $10\text{s}$. The power of the boy during the climb is
(Take $g=10{\text{m/s}}^2)$

• A. $60\text{W}$
• B. $3000\text{W}$
• C. $180\text{W}$
• D. $5\text{W}$

Answer 1

The correct option is C $180\text{W}$


Mass = $30\text{kg}$
$v=$ constant $=\frac{6}{10}=0.6\text{m/sec}$
time required to climb $t=10\text{sec}$.

$\Rightarrow v=$ constant, means $a_{Boy}=0$
i.e., $F_{net}$ on Boy $=0$

$\Rightarrow T=mg$

where, $T$(Tension) is force
applied by boy $=300\text{N}$

Power $\Rightarrow P=Fv$
= $Tv$
$=\left(300\right)\left(0.6\right)$
$\therefore P=180\text{W}$
Hence option C is the correct answer