GO UP, GO DOWN, PUSH GO UP, GO DOWN, PUSH ME, AND THROW ME AWAYME, AND THROW ME AWAY

5-5.1 5-5.1 Illustrate the effects of force (including Illustrate the effects of force (including magnetism, gravity, and friction) on motion.magnetism, gravity, and friction) on motion.

Alfonso Landa

MOVEMENTMOVEMENTIn our world it is possible In our world it is possible

to see that things, to see that things, animals, people… are animals, people… are moving. moving.

How can we know that How can we know that something is moving? something is moving?

Something is moving Something is moving because it is changing because it is changing from one position to from one position to another over time.another over time.

But why is it moving? But why is it moving? What makes it moving?What makes it moving?

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FORCESFORCESWhat make something move is the force. What make something move is the force.

Force is any push of pull from one object to Force is any push of pull from one object to another. Some forces occur when one another. Some forces occur when one force touches another, such as a leg force touches another, such as a leg kicking a ball. Other forces, though, may kicking a ball. Other forces, though, may act without object touching as a compass act without object touching as a compass needle.needle.

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EFECTS OF FORCEEFECTS OF FORCEThere are different effects of forces. They There are different effects of forces. They

can: can: push or pull things forward (thrust)push or pull things forward (thrust)rise objects (lift)rise objects (lift)slow down the object or pull back, slow down the object or pull back, pull down. pull down. can crush, can crush, stretchstretchTwist objects and deform them.Twist objects and deform them.

DIFFERENT FORCESDIFFERENT FORCESThere are different forces that make things move:There are different forces that make things move:

Magnetism

Friction

Gravity

Natural forces

An engine An animal

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GRAVITYGRAVITYWhat goes up, must come down What goes up, must come down

Gravity depends on their masses of the Gravity depends on their masses of the objects and the distance between them. objects and the distance between them. Increasing the mass increases the force, Increasing the mass increases the force, and increasing the distance decreases the and increasing the distance decreases the force. force.

Every object in the universe Every object in the universe is pulling on every other is pulling on every other object because it has mass object because it has mass (Newton’s Law of Universal (Newton’s Law of Universal Gravitation).Gravitation).

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FRICTIONFRICTIONFriction is a force that opposes the motion Friction is a force that opposes the motion

of one object moving past another. Friction of one object moving past another. Friction makes difficult to slide on rough surfaces. makes difficult to slide on rough surfaces.

Friction depends on:Friction depends on: The surfacesThe surfaces How hard the objects are pushed How hard the objects are pushed

together. together. To reduce friction we use To reduce friction we use lubricantslubricants

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MAGNETISMMAGNETISMMagnetism is the Magnetism is the

ability of an object to ability of an object to push of pull on push of pull on another object that another object that has the magnetic has the magnetic property (iron, nickel).property (iron, nickel).

Magnets have two Magnets have two poles: north (N) and poles: north (N) and south (S), Like poles south (S), Like poles repel one another; repel one another; different poles attract.different poles attract.

www.howstuffworks.com/compass.htm

INERTIAINERTIA

Balance forcesBalance forces are forces that act on an object are forces that act on an object without changing its motion. The forces acting on without changing its motion. The forces acting on stationary objects are always balanced. stationary objects are always balanced.

A force that causes an object to change its motion A force that causes an object to change its motion is called an is called an unbalanced forceunbalanced force. .

Inertia is that an object at rest Inertia is that an object at rest tends to stay at rest, and an tends to stay at rest, and an object in constant motion tends object in constant motion tends to stay in motion, unless acted to stay in motion, unless acted upon by an unbalanced forces. upon by an unbalanced forces. (Newton’s First Law)(Newton’s First Law)©Microsoft Clipart

FORCE, MASS AND FORCE, MASS AND ACCELERATION ACCELERATION

Something that is accelerating, changing its Something that is accelerating, changing its speed, is because an unbalance force is acting in it. speed, is because an unbalance force is acting in it.

Acceleration decreases as mass increases as long Acceleration decreases as mass increases as long as force is no changing. as force is no changing.

The unbalanced force on an The unbalanced force on an object is equal to the mass of object is equal to the mass of the object multiplied by its the object multiplied by its acceleration: F= m x a. acceleration: F= m x a. (Newton’s Second Law)(Newton’s Second Law)

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ACTION REACTIONACTION REACTION

When one object pushes on a second object, the When one object pushes on a second object, the second pushes back on the first with the same second pushes back on the first with the same strength.strength.

When a person sits on a chair, the weight is When a person sits on a chair, the weight is pushing down on the chair. A reaction force from pushing down on the chair. A reaction force from the chair pushes back up on the person. the chair pushes back up on the person.

All forces occur in pairs, All forces occur in pairs, and these two forces are and these two forces are equal in strength and equal in strength and opposite in direction. opposite in direction. (Newton's Third Law)(Newton's Third Law)

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