Q. A $60\ kg$ man runs up a staircase in 12 seconds while a $50\ kg$ man runs up the same staircase in 11 seconds. The ratio of the rate of doing their work is
A) $6\ :5$
B) $12\ :11$
C) $11\ :10$
D) $10\ :11$
Explanation
(c) $P = \frac{mgh}{t} \Rightarrow \frac{P_{1}}{P_{2}} = \frac{m_{1}}{m_{2}} \times \frac{t_{2}}{t_{1}}$ [As $h =$ constant]
$\therefore\frac{P_{1}}{P_{2}} = \frac{60}{50} \times \frac{11}{12} = \frac{11}{10}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.