Question

A man carries a load of $50kg$ through a height of $40m$ in $25seconds$. If the power of the man is $1568W$, his mass is:

• A. $5kg$
• B. $1000kg$
• C. $200kg$
• D. $50kg$

Answer 1

The correct option is D $50kg$

$\text{Step 1: Define Power}$

$\text{Power}=\frac{\text{Work Done}}{t}........\left(1\right)$

$\text{Step 2: Work done}$

Work done by external force= Change in potential energy of the man

Work done by external force = $\Delta PE=mgh=(50+m_{man})gh.........\left(2\right)$

$\text{Step 3: Solving above equations}$

Using $\left(1\right)$ and $\left(2\right)$

$\text{Power}=\frac{(50+m_{man})gh}{t}$

Substituting the values
$\Rightarrow 1568=\frac{(50+m_{man})\times 9.8\times 40}{25}$

$\Rightarrow m_{man}=50kg$

Hence option(D) is correct.