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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