1 1 Force and Pressure. 2 What are Forces? A push or pull

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Force and Pressure

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What are Forces?

A push or pull

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Examples of Forces

Squeezing Stretching Twisting Folding

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Object’s shape changes Object’s size changes Stationary object moves

Effects of Forces

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Moving object stops Moving object speeds up or slows down Direction of an object’s motion changes

Effects of Forces

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Weighing scale

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Tsunami

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Weight lifting

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Ultimate frisbee

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Naruto vs Sasuke

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Measuring Forces

S.I unit of force is newton (N) Spring balance used to

measure the amount of force applied

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Types of Spring Balance

Extension spring balance Spring stretches when a pulling force acts

on it Greater force, greater extension Spring attached to a pointer which indicates

the amount of force exerted on the spring

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Types of Spring Balance

Compression spring balance Spring compressed when a pushing force

acts on it Greater force, greater compression Spring attached to a pointer which

indicates the amount of force exerted on the spring

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Forces Around Us

Gravity Friction Magnetism

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Gravity

Gravity is the force that attracts objects to the Earth

Mass is a measure of the amount of matter in a body

Weight is a measure of the gravitational force exerted on the object

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Friction

Frictional force acts when one materials rubs against another

Friction is useful in walking and when applying brakes to stop a car

Constant friction leads to wear and tear Friction produces heat

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Magnetism

Magnetism is the force exerted by a magnet on magnetic materials such as iron and steel

Every magnet has a North pole and a South pole

Like poles repel Unlike poles attract

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What is Pressure?

Amount of force

acting on a unit area A sharp object pierces

a surface more easily than a blunt object

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Calculating Pressure

Pressure = ForceArea

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Applications of Pressure in Everyday Life

Bulldozer Can openers Knife Plane Suction cups