TESLA Simple Machines 2010

The Wheel

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.

ENGAGING SCENARIOFor generations we have been faced with tasks that require us to move an object from one location to another, and we know from our previous investigation, that friction plays a major role in increasing the force required. Think about how challenging tasks would have been 100, 200, and even thousands of years ago when humans had to move large objects without modern machinery. The materials to build Stonehenge and the Great Pyramids were not moved with machines like we have today. Many people believe that the invention of the wheel was one of the most important inventions of all time.

In this investigation you will need to gather and provide evidence of how a wheel can affect the amount of force needed to complete a task (work).

• 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 affect the amount of force needed to complete a task (work).

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New Vocabulary

Wheel:A disk that turns around an axis.

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Wheels have evolved a great deal over time from solid wood rollers in 3300 B.C. to the high-tech, lightweight wheels of today.

Prediction (related to the focus question)

Prediction:I predict that a wheel will/will not reduce the amount of force needed to move an object because ___________________.

Previous KnowledgeShare experiences with wheels related to the focus question.

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Class Predictions (related to the focus question)

Preparing the InvestigationWe are going to test the force and work required to move a brick across a carpeted surface. Each group will be given a spring scale, 1 brick, a meter stick, and 5 wooden dowels.

What are we going to change What are we going to keep the same

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The surface we pull the object acrossCarpet vs. Carpet with Dowels

• The object: brick• The spring scale• The distance we pull the object

Collecting DataWe need to keep track of our data and observations…

Work on Three Different Surfaces

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Method Force(newtons)

Distance(meters)

Work(joules)

brick without dowels

brick with dowels

Making Meaning ConferenceWhich method of pulling the brick required the most work?

Why do you think less force was required to move the brick across the dowels?

What mechanical advantage to wheels provide?

Claims and Evidence

I claim that… I claim this because…

How can a wheel affect the amount of force needed to complete a task (work).

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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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