Friction and Gravity. 1. What is friction? The force that two surfaces exert on each other when they...
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Transcript of Friction and Gravity. 1. What is friction? The force that two surfaces exert on each other when they...
![Page 1: Friction and Gravity. 1. What is friction? The force that two surfaces exert on each other when they rub against each other.](https://reader033.fdocuments.in/reader033/viewer/2022061614/5697bfde1a28abf838cb1f5c/html5/thumbnails/1.jpg)
Friction and Gravity
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1. What is friction?
The force that two surfaces exert on each other when they rub against each other.
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Byproduct of friction…Heat!
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2. What direction does friction act?
• Acts in direction opposite to the objects in motion.
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3. How do you show friction as a force?• An arrow opposite of the object’s
motion
Friction force
Motion
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4. What determines the strength of friction?The types of surfaces (smooth or rough)
and how hard the surfaces push together
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5. What are 4 types of friction?
a. Static friction: acts on object NOT moving:
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b. Sliding FrictionTwo solid surfaces slide over each other
ex: pushing book across desk
ex: once the sled is moving, sliding friction
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c. Rolling Friction
Object rolls across a surface
ex: ball bearings
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d. Fluid Friction
• Solid object moves through a fluid
ex: oil, water, air
(what do you use in your car to reduce friction?)
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• What are two ways in which friction can be useful?
• allows objects to remain in place!
• allows moving objects to stop to avoid colliding with other objects!
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6. What is gravity?
• The force that pulls objects toward each other
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- Friction and Gravity
Universal Gravitation•Two factors affect the gravitational attraction between objects in the universe: mass and distance.
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7. How do you show gravity as a force on Earth?• An arrow toward the center of Earth
Gravity
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8. What is weight?
• The gravitational force exerted on an object
http://youtube.com/watch?v=L55jImEhNZ0
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9. What is the acceleration due to Earth’s gravity?
• 9.8 m/s2
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What is your weight (on Earth)?
Weight = Mass × 9.8 m/s2
Weight = ?
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10. What is free fall?
• When the force of gravity alone causes an object to accelerate downward.
• Causes an object to accelerate downward at 9.8 m/s2
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11. What is air resistance?• Type of fluid friction as an object
moves through air.
• Depends on speed and surface area
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Air resistance
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Free fall:
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Gravity
Air resistance
Net Force
accelerate downward
Free fall:
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Terminal velocity:
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Gravity
Air resistance
0 net force
Move at constant
speed
Terminal velocity:
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Gravity
Air resistance
Net Force
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Gravity
Fluid friction
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Gravity
Rolling friction
Air resistance