friction & gravity
DESCRIPTION
Friction & Gravity. Forces Review. A force is a push or pull on an object. Forces have both size and direction. Forces can be balanced or unbalanced. Friction. Based on your prior knowledge, what is friction?. Friction. Friction is a force that RESISTS motion. (works against it) - PowerPoint PPT PresentationTRANSCRIPT
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A force is a push or pull on an object.
Forces have both size and direction.
Forces can be balanced or unbalanced.
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Based on your prior knowledge, what is friction?
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Friction is a force that RESISTS motion. (works against it)
Occurs when two objects are in contact with one another.
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What two objects are experiencing friction in these examples?› A person walking› A car driving on the street› A boat sailing on a lake› An airplane flying in the air
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Which force represents friction in a car driving down the street?
525 N
1025 N
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Change the surface of the objects› Rougher surface=Greater Friction
Increase the force keeping the objects in contact› Ex. Rubbing your hands together
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Change the surface of the objects› Smoother surface=Less Friction
Decrease the force keeping the objects in contact› Ex. Rubbing your hands together
Use a lubricant (ex. Oil, grease, water)
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Why does a surface covered in ice have less friction than a surface not covered in ice?
Think of some activities that would change if there was no friction.
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Based on your prior knowledge and observations, what is gravity?
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Gravity is a force that attracts objects to each other.
Every object has its own force of gravity.
Gravity PULLS objects towards the center of the object.
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The strength of gravity depends on the objects MASS. › More MASS=More GRAVITY› Most objects are too small to exert a
detectable amount of gravity Gravity increases as you near the
center of the object. What objects gravity do we experience
the most?
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The Less MASS an object has the Less GRAVITY it exerts.
The farther away from the objects center, the less gravity exerted by that object.
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Why do astronauts experience less gravity on the moon?
Denver is on average a mile above sea level while New Orleans is on average 100ft below sea level. At which city will you experience more gravity from the Earth?