Question

(a)Calculate the amount of power generated by a 60-kg person climbing a 2.0-m high flight
of stairs in 7.0 s. (b) Repeat the calculation for the same person running up the stairs in 2.0
s.         .efficiency of the human body in converting food energy into work varies with
activity. When climbing stairs the efficiency of the body is 20%. How much food energy in
kilocalories does the person in problem(12) consume in climbing one flight of stairs? (b)
How much thermal energy is generated by the person climbing the stairs in figure problem
(12)?

Answer 1

(a) Power generated by a person climbing stairs can be calculated using the formula:
Power = work / time
First, calculate the work done by the person:
Work = force x distance
Force = mass x gravity
Force = 60 kg x 9.8 m/s^2 = 588 N
Work = 588 N x 2.0 m = 1176 J
Now, calculate power:
Power = 1176 J / 7.0 s = 168 W
Therefore, the power generated by the person climbing the stairs is 168 watts.
(b) For the person running up the stairs in 2.0 s:
Work = 588 N x 2.0 m = 1176 J
Power = 1176 J / 2.0 s = 588 W
The power generated by the person running up the stairs is 588 watts.
To calculate the food energy consumed in climbing one flight of stairs, we can use the efficiency of the body:
Food energy consumed = work / efficiency
Food energy consumed = 1176 J / 0.20 = 5880 J
To convert this into kilocalories, we can use the conversion factor 1 J = 0.000239006 kcal:
Food energy consumed = 5880 J x 0.000239006 kcal/J = 1.404 kcal
Therefore, the person consumes 1.404 kilocalories in climbing one flight of stairs.
To calculate the thermal energy generated by the person climbing the stairs, we subtract the work done from the food energy consumed:
Thermal energy = Food energy consumed - Work
Thermal energy = 5880 J - 1176 J = 4704 J
Therefore, the person generates 4704 J of thermal energy while climbing the stairs.