TE Activity: Human Power
Contributed by: Office of Educational Partnerships, Clarkson University, Potsdam, NY
Winner - 2009 Premier Curriculum Award for K-12 Engineering
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Human power experinent |
Summary |
Engineering Connection |
| The basic concepts of work, force, energy and power are fundamental physics concepts utilized in many engineering calculations and design. Every engineered device that moves, lifts or pushes requires energy. An engineer must know how to calculate the power and energy needed to do the necessary work or provided the required heat. Most of the world uses metric units to quantify engineering terms. But the USA is still one of the few countries that performs some of its engineering work in the old British system. Metric units are all based on fundamental physics quantities. That makes the metric Joule, Newton and watt much easier to use and calculate than the British Btu (British thermal unit), horse power, pound force, and slug. |
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| Grade Level: 8 (6-8) | Group Size: 3 |
| Time Required: 40 minutes |
Activity Dependency  :Energy Basics |
Expendable Cost Per Group
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Not defined |
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| Keywords: acceleration, energy, force, Joule, horsepower, measurement, Newton, power, work | |
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Related Curriculum
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| subject areas | Data Analysis and Probability Physical Science Physics |
| curricular units | Energy Systems and Solutions |
| lessons | Energy Basics |
Educational Standards :
- National Council of Teachers of Mathematics Math
- National Science Education Standards Science
Learning Objectives (Return to Contents)
- The student will be able to define and contrast energy, work, and power.
- Given mass, distance, and time, the student will be able to calculate work, force, and power using appropriate units.
- Given the conversion formulas, the student will be able to convert between horsepower and kilowatts.
- Students will use measurement tools to apply the concepts of work, power, and energy to a real life example
Materials List (Return to Contents)
Per Class
- Scale (~500-1000 g)
Per Group:
- Stopwatch
- large bottle filled with water (500 mL - 1 L water or soda bottle)
- meter stick
- pole (2-3 cm dowel, ~ ½ m long)
- rope/string to tie bottle to dowel with ½ - 1 m length between
- Activity sheet and data table (one per student)
Introduction/Motivation (Return to Contents)
Power, the rate at which work is done, is now measured in units of watts after James Watt. Mr. Watt built the first steam engine. When he was selling it, he advertised to farmers and miners that it could give more power than a horse. He said that it had 1.5 horsepower. Although the unit of horsepower is still used today, it does not accurately describe how many horses it replaces because not every horse is the same. Not every person is the same either. How many of your own person power does it take to equal a horse? How about to light up a 60 W lightbulb? Do you think you have enough power to do that?
Procedure (Return to Contents)
Before class:
- Prepare the bottle/dowel apparatuses. Fill water bottle full and cap tightly. Tie ~1 m long string to the top of the bottle, the other end to the middle of the dowel.
With the students
1. Have a student demonstrate the basic concept of the human power experiment - (no measurement)
- Hold the dowel horizontally with a hand on either side of the string and with the string and bottle hanging down. The student might need to stand on a chair to hold the dowel high enough to lift the bottle off the floor.
- The student holds the dowel out in front of his/her body and rotates the dowel in his/her hands to raise the bottle as the string wraps around the dowel.
2. Discuss what happened - use discussion to review energy, work, and power- go over equations and units for force, work, power.
- Want to determine POWER
- Power = work/time
- Work = force x distance
- Where Force = mass x acceleration (know acceleration of gravity, need to measure mass)
3. Ask students - if we wanted to determine how much work student just did, what could we measure? (mass, time, distance - can't measure force directly in this case)
4. Introduce Human Power Activity. This activity will require students to collect data for mass, distance and time. The activity sheet lists equipment needed, but you may want to substitute heavier bottles so the students can "feel" the work they do (2-liter or ½ gallon milk jugs work well).
5. Using the data collected in the Activity, calculate average time and apply the appropriate formulas to calculate work and power. Calculate a few of the trials in class, have students finish the calculations for homework.
6. Hold up a 60 Watt light bulb and ask if anybody in the class produced enough power to light the bulb (hopefully no one actually does). Ask if they could produce more power possibly with their legs. (Give the example of the human powered bike headlights).
7. Ask and/or lead a student (on the board) through a calculation of how many of themselves it would take to light the bulb, based on their power output from the activity. # of people to light 60 Watt bulb = 60 watts/power from the activity. (For example, if the student's name was Nate and it took 300 of them to light the bulb, it is therefore a 300 BILLpower bulb (for a student named Bill))
8. If time allows, convert watts to horsepower in activity.
Attachments (Return to Contents)
Assessment (Return to Contents)
Have students complete the activity worksheet and discussion questions and turn in.
Other Related Information (Return to Contents)
This lesson was originally published by the Clarkson University K-12 Project Based Learning Partnership Program and may be accessed at http://www.clarkson.edu/highschool/k12/project/energysystems.html.
Contributors
Susan Powers, Jan DeWaters, and a number of Clarkson and St. Lawrence students in the K-12 , Project Based Learning Partnership ProgramCopyright
© 2008 by Clarkson University, Potsdam NY 13699This unit was developed under National Science Foundation grants No. DUE-0428127 and DGE-0338216. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.
Supporting Program (Return to Contents)
Office of Educational Partnerships, Clarkson University, Potsdam, NYLast Modified: August 11, 2009