Answer to Question #221775 in Physics for Sadia Shafique

Question

In a classic experiment, Robert Downey Jr. (78 kg) and Chris Hemsworth (91 kg) are racing up a flight of 10 stairs. Each stair is 19.7 cm high.

If Chris Hemsworth manages to get up the stairs is 11.5 seconds and Robert Downey Jr. takes 8.1 seconds, who measures the greatest power?

Answer 1

Find the total stairs height they are to overcome:

$$H=0.197·10=1.97\text{ m}.$$

The power is work over time, or change in potential energy over time:

$$P_R=\frac{mgH}{t_R}=186\text{ W }. \\\space\\ P_C=\frac{mgH}{t_C}=131\text{ W }.$$