force
DESCRIPTION
Force. Definition: A push or a pull Force can cause motion SI unit -> Newton (N)= 1 kg x 1 m/s 2 Sometimes pound ( lb ) can be used as a unit for force 1 Newton=0.22481 pounds force. Combining Forces. Balanced Force Equal and opposite forces = ‘balanced’ - PowerPoint PPT PresentationTRANSCRIPT
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FORCEDefinition:
A push or a pull Force can cause motion
SI unit -> Newton (N)= 1 kg x 1 m/s2
Sometimes pound (lb) can be used as a unit for force
1 Newton=0.22481 pounds force
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COMBINING FORCESB. Balanced Force
Equal and opposite forces = ‘balanced’ Balanced forces give no motion
No motion of hands
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COMBINING FORCES Unbalanced force – more force in one direction (net
force)
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NET FORCE Bigger force to the right Smaller force to the left Net force to the right
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III. FRICTION AND GRAVITYA. Friction – a force that opposes motion
1. Caused by the interaction between two touching surfaces rubbing against each other
2. Four Types
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A. STATICFriction that acts on something that is not moving
No heat or wear is generated
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B. SLIDING Force resulting when pushing or pulling an
object over a surface.
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C. ROLLING Contact is reduced because of rollers or wheels or
ball bearings.
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D. FLUID FRICTION Resistance from a “fluid” Fluids are liquids and gases.
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REDUCING FRICTION A smooth surface does not demonstrate as
much friction as a rough surface. Waxing, oiling, etc. can be used to reduce
friction.
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COEFFICIENT OF FRICTION µ= “coefficient of friction” represents the
roughness of the surfaces in contact.
In reality there two main subtypes:
1. µs - Static friction to get it moving2. µk- Kinetic friction to keep it moving µs > µk needed for movement to occur
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B. Gravity – force of attraction between two objects---> pulling force
Factors Affecting Gravitya. Mass – more mass, more gravityb. Distance – closer, more gravity
http://www.exploratorium.edu/ronh/weight/
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END CHECK- COMPLETE ON SEPARATE SHEET OF PAPER 1. Describe three ways in which a car’s velocity
will change
2. Identify a one situation involving unbalanced force and one situation involving balanced force. Explain how it each affect the motion of an object.
3. Arrange the following pairs of surfaces in order of most friction to least friction A shoe sole and a waxed basketball court A shoe sole and the frozen surface of a lake A shoe sole and the sidewalk
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END CHECK- COMPLETE ON SEPARATE SHEET OF PAPER 4. Explain why Venus, which is slightly less
massive than Earth, experiences a stronger gravitational pull from the sun than Earth does.
5. What is the average acceleration of a scooter that starts at rest and moves straight ahead at 12 m/s in 24 s.
6. Which will be moving faster after 3.0 s, a cyclist maintaining a constant velocity of 15 m/s straight ahead or a race car accelerating forward from a stoplight at 4.0 m/s2?