Lab: Computing Personal Power
Objective:
Compute your personal power while walking and then hurrying up a flight of stairs.
Hypothesis:
Does a person do more work walking up a flight of stairs or running up the same stairs?
Procedure:
Gathering Data
1. You will be working in groups of two.
2. Find your weight, in pounds, using the scale at the front of the
room.
3. Convert your weight into Newtons using the conversion factor
4.42 N/lb.
4. Measure the height of the stairs that you will be climbing.
Measure the height of one step then count the number of steps.
5. Time yourself three times each walking and hurrying up the
stairs.
Weight
Pounds
Newtons
Height of stairs:__________________________
Time (s)
Trial
1
2
3
Average
Walking
Hurrying
Calculations
6. Calculate the work done when climbing the stairs slow and steady.
7. Calculate the work done when climbing the stairs rapidly.
8. Compute the power, in watts, that you generated in walking up the stairs. Pay
attention to units!
9. Compute the power, in horsepower, that you generated in walking up the stairs.
(1 horsepower =746 Watts).
Personal Power
Trial
Walking
Watts (J/s)
HP (ft-lb/s)
Hurrying
Watts (J/s)
HP (ft-lb/s)
1
2
3
Average
Analysis Questions:
1. Did climbing the stairs slow and steady or rapidly do more work? Which case did
you exert more power?
2. A large and a small person climb a flight of stairs in the same amount of time.
Which person generated the greatest horsepower? Explain
3. Marissa does 3.2 J of work to lower the window shade in her bedroom a distance
of 0.8 m. How much force must Marissa exert on the window shade?
4. The coyote, whose mass is 20.0 kg, is chasing the roadrunner when the coyote
accidentally runs off the edge of a cliff and plummets to the ground 30.0 m below.
A. What force does the ground exert on the coyote as he makes a coyote
shaped dent 0.420 m in the ground? (The coyote does 6000 J of work).
B. If the coyote falls for 2.47 second, how much power does he generate?
C. Compute how much horsepower the coyote generates?