The Basics of FORCES

On p. 24 you are going to take Cornell style notes

*Take at least 1 note per slide

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If you need more space use p. 25

Essential Question:

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What are forces and how do they affect motion?

Why are forces so important?

What is motion?

• Motion is a change in position
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• Speed is the change in distance in a specific amount of time
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• Acceleration is a change in the speed

Not

moving

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moving

What causes acceleration?

Changes in motion mean accleration

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• going faster
• going slower
• changing direction

How do we calculate speed?

Distance Time = speed

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Jane runs for 3 seconds and moves 12 meters.

Her speed is 12/3= 4 m/s

So what exactly is a force and how do we measure it?

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• Forces can be a push

• Forces can be a pull

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• A force is a push or pull, or any action that has the ability to change motion.

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• Forces have Size and direction
• Shown with a vector (arrow with a number)

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5 N

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How do we measure a force?

The tool to measure force is a spring scale.

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• Force are measured in Newtons.
• One pound of force equals 4.48 newtons.

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How do we know the total force?

We calculate net force using a diagram

Some examples of forces are:

Friction

Buoyancy

Tension

Gravity

Compression

Gravity

• Pulls objects with mass together

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• More mass =more gravity
• Closer together =more gravity

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Friction is….

• A force that opposes motion between two surfaces in contact

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• It can prevent or slow motion

Magnetism is….

Learn more at http://www.explainthatstuff.com/magnetism.html

the motion of charged particles

This causes some materials to exert a force of attraction or repulsion on other materials

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How can a rubber band move a car?

Tension is….

the force transmitted through a rope, string or wire when pulled by forces acting from opposite sides

Elastic force is…the force that allows some materials to return to its original shape after being stretched or compressed

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