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Science 3rd, unit 8

Feb, 2014

SCIENCE 3rd grade

UNIT 8

FORCES & MACHINES

J. CĂŠsar Brazo Mur

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

FORCES

Definition

FORCES are actions, applied by Nature or people, that cause different effects on objects.

are

ACTIONS applied by

NATURE Wind, water, earthquakes...

PEOPLE With our BODY

Using MACHINES

They cause different effects on objects (Move them, change their shape, etc.)

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

FORCES CONTACT FORCES

NON-CONTACT FORCES

types

When something touches an object and makes it move or change its shape.

When nothing touches an object but there is a force that makes it move.

Examples: When a footballer shouts the ball, his foot touches the ball.

Pushing, pulling or lifting objects are other examples.

Two common types of non-contact forces are: - Magnetism: magnetic objects attract metals without touching them - Gravity: The force of attraction of the Earth attracs objects and make them fall down

GRAVITY

LIFTING

PUSHING

PULLING

El Tomillar, J.C. Brazo

MAGNETISM

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Science 3rd, unit 8

Feb, 2014

IMPORTANT DEFINITIONS MAGNETISM: Property of some metals to attract other metals. Magnets have a north and a south poles.

Mind well!: equal poles, repel each other.

Different poles attract each other.

N

GRAVITY: Property of attraction of the S Earth's on objects.

The Earth is like a big magnet, also with north and south poles.

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

M A C H I N E S

Feb, 2014

Definition "Machines are tools that make work easier or faster"

El Tomillar, J.C. Brazo

Types * Simple machines Machines that have a simple mechanism

A pair of scissors is an exmaple of simple machine

* Complex machines Machines made up of complex mechanisms or many simple machines

Cars and bikes are complex machines

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Science 3rd, unit 8

Feb, 2014

Bikes are complex machines.

They're made up of many simple machines

SEAT

HANDLEBARS

BREAKS

WHEEL

PEDALS CHAIN

Laptops are complex machines.

They're made up of complex elements

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

They help us complete daily tasks more easily and with less effort

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

PARTS OF A LEVER

FORCE

Effort we apply to move the resistance

R D BA I G I R Solid bar that moves R

C TAN ESIS

Heavy load at the other side of the rigid bar

El Tomillar, J.C. Brazo

when a force is applied

E

FULCRUM Part that supports the rigid bar

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Science 3rd, unit 8

Feb, 2014

PARTS OF A LEVER RES ISTA NC

E

FORCE

RIG ID B AR POINT OF SUPPORT

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

PARTS OF A PULLEY WHEEL It moves on an axis

GROOVE A rope moves around it

Pulleys help us raise heavy objects more easily

AXIS It permits the wheel rotates

ROPE

FORCE

RESISTANCE

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

PARTS OF A PULLEY WHEEL

GROOVE AXIS

ROPE

RESISTANCE

FORCE

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

SCREW SHAFT

It turns and passes the movement to another part

El Tomillar, J.C. Brazo

INCLINED PLANE

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Science 3rd, unit 8

Feb, 2014

By rotating, the screw moves itself or another object

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

By rotating, the screw moves itself or another object

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

By rotating, the screw moves itself or another object

El Tomillar, J.C. Brazo

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Science 3rd, unit 8

Feb, 2014

WHEEL Circular object that spins around an

El Tomillar, J.C. Brazo

AXLE

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Science 3rd, unit 8

Feb, 2014

WEDGE It is made up of TWO INCLINED PLANES

We use it to separate things

El Tomillar, J.C. Brazo

An axe is an example of wedge

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