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1 Simple Machines Mike McKee University of Central Florida Orlando, Florida October 7, 2006
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Simple Machines
Mike McKeeUniversity of Central Florida
Orlando, FloridaOctober 7, 2006
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Simple Machines
□What is the purpose of a simple machine?
□What should you be measuring as evidence of this purpose?
□How will this guide your calculations and help you determine what to measure?
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Four Types of Machines
□Lever
□Pulley
□Inclined Plane
□Wheel and Axle
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Select a station
In 15 minutes:□Determine the IMA□Determine the AMA□Determine the Efficiency□Record your procedures□Report back to the group
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Ideal Mechanical Advantage
PULLEYS:
IMA = Distance you move Displacement of the object
Problems with this?Units?
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Actual Mechanical Advantage
PULLEY’S:
AMA = Force (weight) of object Force you measure
Units?Problems?
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Efficiency
□AKA energy loss from friction!□Why do we care?
Efficiency = AMA x 100% IMA
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Pulleys
Why the difference?
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Pulleys
□Why not 20 Newtons?
http://www.walter-fendt.de/ph14e/pulleysystem.htm
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Inclined Plane
□Why is the height called the resistance distance?
http://www.walter-fendt.de/ph14e/lever.htm
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Inclined Plane
IMA = Length of Ramp Vertical Height of Ramp
How can you improve IMA?
http://www.walter-fendt.de/ph14e/inclplane.htm
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Levers
Three types. How are they Different? Which is best? Examples of their use?
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Levers
IMA = Length of Effort Arm Length of Resistance Arm
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Wheel and Axle
□What do you change to improve mechanical advantage?
□How did you measure distance moved and displacement?
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IMA = Radius of Effort circle Radius of Resistance circle
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Measuring AMA
AMA = Force of weight or object Force you apply
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Actual Mechanical Advantage
Measure force with spring scale where you pull!
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Actual Mechanical Advantage
□What’s wrong with this picture?
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ABC - CBV
As you prepare, have students construct their own meaning. Have students do the Activity Before Concept, then Introduce the Concept, then follow up with Vocabulary.
Always spend as much or more time discussing the results and concepts than they did performing the experiment!
This is the heart of Inquiry, which we did today.
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Whiteboarding
Whiteboards can be purchased from Home Depot or Lowes. Have them cut into 6 pieces and use with groups.
To promote discussion, have a mall walk, in which students walk around to other whiteboards and then ask questions of the groups.
Cut pieces into 1 x 1 for individualized formative assessment.
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Contact
Mike McKeeUniversity of Central [email protected]
Weather Lessons and Videos:www.wesh.com - Click on Hank and Hannahwww.weatherplus.com – University Archives
Other professional development:www.inquiryinstitute.org ;
www.floridascienceolympiad.org
