Physics 11
Dr. Wang
Physics 11 Work, Energy, and Power Lab
Names: Gurick Dhillon
Period: 1-1
Joseph Dobrzanski
Date: 07 Apr 15
Objective:
To find the power of a human and how it compares to the class
Materials:
-Flight of stairs
-Measuring utensil (ruler, measuring tape etc.)
-Human test subject
-Stopwatch
-Weighing scale (bathroom scale)
Procedure:
1. Find/gather all materials
2. Measure your mass with the bathroom scale
3. Measure the height of the flight of stairs with a measuring utensil [ruler] (measure each
step and add the collective heights together)
4. Measure the time it takes you to climb the flight of stairs with the stopwatch
5. Record data and calculate the test subject’s power output
6. Communicate results to the class
7. Finish lab, conclude, hand in
Data:
Name:
Time (s): Height Climbed (m): Mass (kg): Weight (N): Work (J): Power (W):
Gurick
3.95
3.4010
79.38
779
2650
670.
Joseph 3.54
3.4010
56.70
556
1890
534
Analysis:
1) Calculations for:
Height climbed:
15.05+14.30+14.40+14.50+14.55+14.80+14.80+14.80+14.60+14.40+14.90+14.50+
15.00+15.10+15.10+14.40+15.00+15.20+14.90+14.90+14.70+14.90+15.30 = 340.10cm
= 3.4010m
Gurick:
Weight: F=m*g F = 79.38kg * 9.81m/s² = 778.704N → 779 N
Work: W=F*d
W = 778.704N * 3.4010m = 2648.37J → 2650 J
Power: P=W/t P = 2648.37J / 3.95s = 670.47W → 670. W
Joseph:
Weight: F=m*g F = 56.70kg * 9.81m/s² = 556.227N → 556 N
Work: W=F*d
W = 556.227N * 3.4010m = 1891.728J → 1890 J
Power: P=W/t P = 1891.728J / 3.54s = 534.386W → 534 W
2) [See attached page for graph and slope calculations]
3) Slope of the graph: 4.3428 W/kg → 4.34 W/kg
Conclusion:
1. One source of random error, is misreading the measurements of the height of each stair
by not looking at the ruler at eye level. By being slightly above or below the actual height
of the stair, height, work, and power may be slightly off. Another random error is
measured time. Human reaction time and inaccuracies in gauging when exactly each
person started and stopped, affects the how long each person took to climb the stairs
and by extension the power of each person. A final random error is the effort people put
in to climbing the stairs, because not everyone will try their hardest or the same X% of
their best. This is clearly seen when people walk up the stairs vs. when they run up the
stairs. This again, this affects their power output.
2. One source of systematic error is the staircase that our class had to climb. Around ⅔ up
the staircase, you have to turn 180-degrees around a bend before climbing up the last
bit of stairs. This means that while it took longer to climb the stairs, no more horizontal
distance was traveled. In effect, this makes the power output slightly lower than it would
otherwise be, (as time, the number dividing work, would be greater and would make the
product is smaller.)
3. Our group’s power output, (670. W for Gurick and 534 W for Joseph) were definitely part
of the trend of more mass = more power, and was above the class’s power average.
This trend though is not true in every case, as Gurick has the most power despite not
having the most mass. Joseph had an average mass as well, but had more power than
many of those who had equal or more weight than him. (This is probably because this
chart and trend does not account for effort, which influences people’s time and power.)
4. The slope of the graph indicates that per every 1 kg someone weights, they will be able
to generate 4.34W. (In a general sense) this also shows that there is a trend where the
more massive someone is, the more power they will be able to output. Individual results
seem to vary by a large margin because other factors such as effort and muscle mass
are not taken into account. Generally though, larger people have more muscles (the
means for which they generate motion) and therefore more power.
5. Our data shows that mass plays a factor in human power output. This reveals part of
why different athletic physiques affect what they excel at. A sprinter would want more
power to convert more energy into motion, so would be generally heavier than their long
distance counterparts. Burning out early by using too much energy too quickly in a long
distance event is why marathon runners would be lighter. Less mass is a plus, because
running will take less work (with less baggage to pull around,) and more mass is mostly
for having a higher maximum velocity. Useful when you only need to run 100m, but
wasteful when you cannot maintain that speed for half the marathon.