Human Power

Purpose: To determine the power output of a person.

Vertical distance between the ground floor and the second floor: 4.29 m
Time 1: 13.47 s

Time 2: 13.31 s   

average time: 13.39 s

F = 618 N

delta PE = mgh

delta PE = 618*4.29

delta PE = 2651.22

Power = 2651.22/13.39

Power = 198 watts

Horse power = 198*.00134102209

Horse power = .2655

Stair diagram

Questions:

1. Is it okay to use your hands and arms on the hand railing to assist you in your climb up the stairs? Explain why or why not.

- It is not okay because it can change the time it takes you to climb the stairs. By changing the time, it changes the power exerted. 

2. Discuss some of the problems with the accuracy of this experiment.

- One problem could be the measurement of the stairs. It could have been off a little. Also, the time. Since the person climbing the stairs wasn't timing themselves, they might not have started walking at the exact time the person started the timer. Along with that, when stopping, the timer may not have stopped exactly when they got to the top of the stairs.

Conclusion questions:

1. Two people of the same mass climb the same flight of stairs. Hinrik climbs the stairs in 25 seconds. Valdis takes 35 seconds. Which person does the most work? Which person expends the most power? Explain your answers.

H: (600)(4.29)/25 = 108.14w(.00134102209) = .145 hp

V: (600)(4.29)/35 = 77.47w(.00134102209) = .104 hp

- Work doesn't depend on time so the work is the same. Hinrik exerts more power because it was a shorter amount of time. Power = work/time

2. A box that weighs 1000 newtons is lifted a distance of 20 meters straight up by a rope and pulley system. The work is done in 10 seconds. What is the power developed in watts and kilowatts?

(1000)(20)/10 = 2000w(1kw/1000w) = 2kw

3. Brynhildur climbs up a ladder to a height of 5 meters. If she is 64 kg:

a) what work does she do?

work = mgh

work = (64)(9.8)(5)

work = 3136J

b) what is the increase in the gravitational potential energy of the person at this height?
- It is depended on the potential energy

c) where does the energy come from to cause this increase in PE?
- Chemical energy

4. Which requires more work: lifting a 50 kg box vertically for distance of 2 m, or lifting a 25 kg box vertically for a distance of 4 meters?

A: work = (50)(9.8)(2) = 980J

B: work = (25)(9.8)(4) = 980J

- The work is the same.

Conclusion: In this lab i learned how much power it takes to climb the stairs. I learned that the amount of time it takes is what controls how much power it is. One problem could be the measurement of the stairs. It could have been off a little. Also, the time. Since the person climbing the stairs wasn't timing themselves, they might not have started walking at the exact time the person started the timer. Along with that, when stopping, the timer may not have stopped exactly when they got to the top of the stairs. To make this lab improved, it would be smart to have each person time themselves.