11/25/2013

Human Power

P = ΔEΔT

Daniella Lucie JacquesGrade 11 – 2013

Presented to Mme Neena

Purpose:

Power is determined by the equation, P =ΔEΔT , and measured in Joules. A Mini Investigation activity

found on page 251, of the Nelson’s University Preparation Physics 11 textbook, allows for a study of Power, more specifically Human Power. The activity entails of a comparison, between students, of their average Power required for walking and of running up a flight of stairs.

Materials:

A Bathroom Scale A Measuring Tape A Staircase Stopwatch (iPhone) Pencil(s) Paper(s) – a place to take note of information Teacher – Mme Neena Subjects/Students – Eric, Emma, Daniella

Method:

Part A:

1. Use scale to measure the subjects’ mass, and then calculate their weight in Newtons. 2. Use the measuring tape to measure the flight of stairs. To do so in a quicker fashion, one may

simply measure the height of one stair and multiply it by the number of stairs. 3. Use the stopwatch to measure how long it takes (measured in seconds) for each subject to walk

up the stairs at a constant speed. Subjects must walk up the stairs at least three times and then calculate their average time from those results.

4. Use stopwatch to calculate the time it takes (measured in seconds) each subject to run up the stairs at a constant speed and without skipping any stair or stairs. Each subject must repeat this at least three time before determining their average time from the results.

Part B:

1. Calculate each subjects’ Potential Energy.2. Calculate each subjects’ average power produced by walking up the stairs.3. Calculate each subjects’ average power produced by running up the stairs.

Part c: Analysis & Conclusion

1. Did the subjects have greater power walking or running up the stairs? 2. Compare the power of the subjects produced while walking and running up the stairs to the

power of a 100 W light bulb. Which produces the most power? Why?

Data:

Part A:

Mass/Weight:

Subject: Daniella Eric Emma(Mass X 9.8)=Weight in Newtons

125lbs=56.6Kg(56.6Kg X 9.8)=554.68N

132lbs=59.8Kg(59.8Kg X 9.8)=586.04N

115lbs=52.1Kg(52.1Kg X 9.8)=510.58N

Stairs:

Number of stairs: 22 stairsHeight of 1 stair: 19 cm in height = 0.19 m in heightTotal: (length of stairs) 22 X 0.19 = 4.18 m

Time Trials: Walking up the stairs

Subject: Trial 1: Trial 2: Trial 3: Average:Eric 14.1 sec. 14.7 sec. 14.1 sec. 14.3 sec.Daniella 14.2 sec. 14.6 sec. 14.2 sec. 14.33 sec.Emma 12.9 sec. 14.8 sec. 13.6 sec. 13.76 sec.

Time Trials: Running up the stairs

Subject: Trial 1: Trial 2: Trial 3: Average:Eric 6.3 sec. 5.0 sec. 5.0 sec. 5.43 sec.Daniella 5.6 sec. 6.2 sec. 5.6 sec. 5.8 sec.Emma 6.1 sec. 5.8 sec. 5.8 sec. 5.9 sec.

Part B:

Potential Energy: Mass X Gravity X Height (mgh) – measured in Joules (J)

Subject: mghEric 59.8Kg X 9.8 X 4.18m = 2449.52 JDaniella 56.6Kg X 9.8 X 4.18m = 2318.56 JEmma 115Kg X 9.8 X 4.18m = 2134.22 J

Power: Walking up the stairs: P =ΔEΔT

Subject: Trial 1: Trial 2: Trial 3: Average:Eric 2449.52J

14.1 sec .=173. 7W2449.52 J

14.6 sec .=166.6W 2449.52 J

14.1 sec.=173.7W 2449.52 J

14.3 sec.=171.30W

Daniella 2318.56J14.2 sec .

=163.4W 2318.56 J14.6 sec .

=158.8W 2318.56 J14.2 sec.

=163.4W 2318.52 J14.33 sec .

=161.73W

Emma 2134.22 J12.9 sec.

=165.4W 2134.22 J14.8 sec .

=144.2W 2134.22 J13.6 sec .

=156.9W 2134.22 J13.76

=155.73W

Power: Running up the stairs: P =ΔEΔT

Subject: Trial 1: Trial 2: Trial 3: Average:Eric 2449.52 J

6.3 sec .=388.8W 2449.52 J

5.0 sec.=489.9W 2449.52 J

5.0 sec.=489.9W 2449.52 J

5.43 sec.=455.86W

Daniella 2318.56 J5.6

=414W 2318.56 J6.2 sec .

=373.9W 2318.56 J5.6

=414W 2318.56 J5.8 sec .

=400.63W

Emma 2134.22 J6.1 sec.

=349.9W 2134.22J5.8 sec .

=367.9W 2134.22 J5.8 sec.

=367.9W 2134.22 J5.9 sec .

=361.86W

Part C:

Analysis:

1. Did the subjects have greater power walking, or running up the stairs?

Referring to the data tables from Data: Part B: and the graphs below; it would appear to be that the subjects exerted more power when running up the stairs than walking. Each subject, for all trials, maintain the same Potential Energy, but their speed quickens and thus the time value is smaller than previously. Therefore with the same Potential Energy, but a smaller time value when running will allow for more power to be produced. Another factor could be the fact that, with a greater mass one has a greater Potential Energy and therefore will most likely have greater Power than someone with less Potential Energy.

Trial 1: Trial 2: Trial 3:0

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40

60

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100

120

140

160

180

200

Power: Walking up the stairs

Eric Daniella Emma

Trial 1: Trial 2: Trial 3:0

100

200

300

400

500

600

Power: Running up the stairs

Eric Daniella Emma

2. Compare the power of the subjects produced while walking and running up the stairs to the power of a 100 W light bulb. Which produces the most power? Why?

Comparing the values it seems that running and even walking up the stairs produces more power than 100 W light bulb. Although walking up the stairs produces only a little more than 100 W, as the running up the stairs clearly produces nearly four times greater power than the bulb. This could be because the subjects had greater ∆ E than the light bulb.

Power:Walking

Bulb Eric Daniella Emma

Power: Running

Bulb Eric Daniella Emma

The results show that the Mini Investigation on page 251 of the Nelson’s University Preparation Physics 11 textbook is an efficient activity to demonstrate Power, more particularly Human Power. The activity allows students to observe how certain factors such as mass and speed impacts upon the quantity of Power.