Question

A person lives on the third floor of a building and he runs up the stairs three times a day. Each floor has 24 steps and height of each step is 15 cm.

              a) If the person mass is 60 kg calculate how much energy he uses each day.

              b) If he runs from first floor to the third floor in 20 seconds, calculate the person power output.

Answer 1

a) The person runs up 3 floors three times, climbing 24 steps each of 15 cm=0.15 m

So, displacement is

So, amount of work done is equal to the product of the weight of the person and the displacement.

This amount of work done is stored as energy. So, energy usd per day is 6350.4 J

b) It takes 20 s to run from first floor to third floor. So, to climb up 3 times it takes 60 s.

So, power output is