Question

A man $M_1$ of mass 80 kg runs up a staircase in 15 s Another man $M_2$ also of mass 80 kg runs up the stair case in 20 s. The ratio of the power developed by them $\left(P_1/P_2\right)$ will be :

• A. 1
• B. 4/3
• C. 16/9
• D. None of the above

Answer 1

The correct option is B 4/3

$M_1=M_2=80kg,t_1=15sec,t_2=20sec$

Let distance covered $=s$

$\frac{P_1}{P_2}=\frac{F_{1}S{t}_2}{F_{2}S{t}_1}=\frac{M_{1}g{t}_2}{M_{2}g{t}_1}$

Since,$M_1=M_2=80kg$

$\frac{P_1}{P_2}=\frac{t_2}{t_1}$

$\frac{P_1}{P_2}=\frac{20}{15}$

$\frac{P_1}{P_2}=\frac{4}{3}$