TESLA Simple Machines 2010

Force and Work

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.

ENGAGING SCENARIO

In this unit we are going to investigate a variety of simple machines to determine how they can be used to make work easier and complete tasks. Before we can investigate any of the machines, we must first understand the relationship that exists between force and work. As groups of scientists, you will be asked to work with some new materials and keep accurate records in your scientist notebook that will support your understanding of the relationship that exists between force and work.

• What is the problem we need to solve? • What do we need to investigate?

Focus Question (What is the problem?)Focus Question (What is the problem?)

Do certain objects require more force and an increased amount of work to lift?

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New VocabularyNew Vocabulary

Force:• A push or pull on an object.

Newton:• A unit of measurement that

is used to measure the amount of force that is applied to an object.

Spring Scale:• The tool that we will be

using to measure force in Newtons.

• Demonstrate how to read and zero a spring scale.

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New VocabularyNew Vocabulary

What is the difference between someone pushing against a wall and someone pushing against a desk?

Have 2 Scientists Demonstrate

Joule:• A unit of measurement that is

used to measure the amount of work that is accomplished.

Work:• When an object moves as a result of force.• The wall did not move, so no work was accomplished• The desk moved, so work was accomplished

Work = Force x Distance

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# Joules = # Newtons x # Meters

Focus Question (What is the problem?)Focus Question (What is the problem?)

Do certain objects require more force and an increased amount of work to lift?

Prediction (related to the focus question) Prediction (related to the focus question)

Prediction:I predict that __________ because____________If _____________________Then___________________

Prediction:I predict that __________ because____________If _____________________Then___________________

Previous Knowledge Previous Knowledge

Share experiences with force and work related to lifting objects.Share experiences with force and work related to lifting objects.

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Class Predictions (related to the focus question) Class Predictions (related to the focus question)

Preparing the InvestigationPreparing the InvestigationEach group is going to lift a variety of objects with the spring scale from the floor to the top of their desks. We are going to need to:

• determine the Newtons of force required to lift each object• measure the distance each object is lifted• calculate the amount of work done in joules

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

The Object Lifted• Determine and record a set of

appropriate objects to test as a class

• Objects cannot exceed the weight limit of the spring scales…

No people, desks, or chairs

• Distance the object is lifted• The scale the object is lifted with• The unit we use to record our

distances (meters)• Raise the objects at a slow and

steady rate

Designing a Controlled Experiment

Collecting DataCollecting Data

Which items do you think will require the most force to lift?Which items do you think will require the most work to move?

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Making Meaning ConferenceMaking Meaning Conference

What do you see as the relationship between force and work?

Which objects required the most force to lift? The least force?

Which objects required the most work to lift? The least work?

Claims and EvidenceClaims and Evidence

I claim that… I claim this because…

Do certain objects require more force and an increased amount of work to lift?

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Reflection/ConclusionReflection/Conclusion

Revisit your original prediction… Explain how the evidence did or did not support your original prediction?

My prediction was accurate or was not 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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