Question

b) A man who has a mass of 80 kg can run up a flight of stairs of 20 steps, in 5 seconds. Given that each step is 20 cm high, how much power does the man use to run up the flight of stairs?

Answer 1

Given:

$m=80\:\rm kg$

$n=20$

$t=\rm 5\: s$

$h_0=0.2\:\rm m$

The power of a man

$$P=\frac{W}{t}=\frac{mgh}{t}=\frac{mgnh_0}{t}$$

$$P=\rm\frac{80*9.8*20*0.2}{5}=627\: J$$