The Wheel and Axle
TESLA Simple Machines 2010
The Big Idea of this Investigation
A simple machine is a mechanical device that
makes work easier by magnifying, modifying,
transferring, or changing the direction of applied
force. Simple machines are the elementary
"building blocks" of which all complicated
machines are made.
Knowledge We Will Build on From Prior Investigations
Force is a push or pull applied to an object.
Work = Distance X Force
Friction is the number one enemy of simple machines. It
increases the amount of force needed to do work.
Wheels reduce the amount of friction between an object and
the surface over which it moves.
ENGAGING SCENARIO
In your previous investigation you discovered how the
wheel, one of the most important inventions of all time, can
be used to reduce friction and decrease the amount of force
needed to move an object. In this investigation I need you
to investigate how a wheel and axle can be used to magnify
force.
• What is the problem we need to solve?
• What do we need to investigate?
Discuss ideas with a partner for a possible focus question.
Your focus question should be connected to what the scenario
wants us to do…
Focus Question
(What is the problem?)
How can a wheel and axle be used together to magnify
(increase) force and make work easier?
Previous Knowledge
Share experiences with wheels and axles related to the focus question.
Prediction (related to the focus question)
Prediction:
I predict that _______________ because____________
If _____________________Then___________________
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Class Predictions (related to the focus question)
New Vocabulary
Axle
•a shaft on which a wheel revolves.
If the wheel and axle are
fixed (connected
together), then one
revolution of the axle
causes one revolution of
the wheel
What happens to the wheel when you turn the axle?
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Work = Force x Distance
Work = One Revolution
Distance = ?
•How far must the wheel and axle travel to complete one
revolution?
Tractor Cars
How can you make your car move under power? !Force!
Work = Force x Distance
Where did the force to move the wheels come from?
When the car rolls are the
wheel and axle performing
the same amount of work?
Are the wheel and axle
traveling the same distance?
Is the force applied to the
axle equal to the force
applied to the wheel?
Work = Force x Distance
Does it require more force to wind the rubber band by the axle
or the wheel?
If you used a larger wheel, would it require more or less force to wind the
rubber band? What if you used a smaller wheel?
What relationship exists between the circumference of the wheel and axle
Claims and Evidence
How can a wheel and axle be used together to magnify
force and make work easier?
I claim that…
I claim this because…
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Reflection/Conclusion
Revisit your original prediction… Explain how the evidence
did or did not support your original prediction?
My prediction was accurate because…..
I wish to revise my prediction because…
What did you learn…
What really surprised you…
What new questions do you have…
What would you like to know more about…
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