Question

A man with a mass of 67.0 kg runs up four flights of stairs in 15.0 secs. The

man has gone a vertical distance of 90 cm. Determine the amount of work

done by the man to elevate his body to this height. Assume that his speed

is constant. 

Answer 1

The work is equal to the change of potential energy:

$$W=\Delta E=mg\Delta h=591\text{ J}.$$