TESLA Simple Machines 2010

The Wheel and Axle

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

Work = Distance X Force

Force is a push or pull applied to an object.

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 SCENARIOIn 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?

Prediction (related to the focus question)

Prediction:I predict that _______________ because____________If _____________________Then___________________

Previous Knowledge

Share experiences with wheels and axles related to the focus question.

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Class Predictions (related to the focus question)

New Vocabulary

Axle• a shaft on which a wheel revolves.

What happens to the wheel when you turn the axle?

If the wheel and axle are fixed (connected together), then one revolution of the axle causes one revolution of the wheel

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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 DistanceDoes 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…

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