Personal Power Lab
Introduction
A person is a machine which has a
power rating
. Some people are more powerful than others; that is, they are capable of doing the same amount of work in less time or more work in the same amount of time. In the Personal Power lab, students determined their own personal power by doing work on their bodies to elevate it up a flight of stairs. By measuring the force, displacement and time, we are able to measure our personal power rating. Suppose that a student elevates her 60-kg body up the 2.0 meter stairwell in 2.1 seconds. If this were the case, then we could calculate the student’s
power rating
. It can be assumed that the student must apply a 588-Newton upward force upon the stairs to elevate her body.
Force = mass x gravity
Work = Force x displacement
1 watt = 1 Joule / sec
Power = Work / time = 588 N x 2.0 m / 2.1 seconds
Power = 560 watts
Objectives
The student will
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1. Use the measurements of mass, distance and time to calculate energy, work and power.
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2. Correlate how much power is needed by the student to elevate themselves with how much is needed to run house hold utilities.
Materials
Stop watch, meter stick, calculator
Procedure
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1. Measure and record your body mass (in kilograms).
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2. Measure and record the height of the steps that will be used.
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3. Run the stairs, two steps at a time, at three different speeds (slow, medium, maximum effort). Make sure you maintain a constant speed throughout each run. Also, make sure you run consistently (check the time for each trial - for a given speed [slow, medium, maximum], the times should be within 0.05 s of each other).
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4. Record the time for each run. Repeat each speed three times. Allow a one minute rest between the maximum effort trials.
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5. Enter all data into the spreadsheet with appropriate formulas to calculateenergy, work, and power.
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6. Graph Average Work and Power vs. Speed for each group member. Also make a composite graph (average of each member’s averages) of work and power vs speed
Mass
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Displacement
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Speed
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Trial
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Time
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Work
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Power
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Energy
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Slow
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1
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2
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3
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Average
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Medium
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1
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2
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3
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Average
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Fast
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1
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2
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3
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Average
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