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31 Cards in this Set
- Front
- Back
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When does motion occur?
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When an object changes position over time relative to a reference point
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How is motion described?
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Cardinal directions
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Define speed.
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Distance traveled divided by the time it took to cover the distance
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Define velocity.
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An object's speed in a particular direction, viewed as the rate of change in an object's position
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What is constant velocity?
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When velocity doesn't change
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When does velocity change?
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When speed or direction change
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Define Acceleration.
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It is the rate at which velocity changes ( V2 - V1/change time
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What relationship does velocity and acceleration share?
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Increase in velocity = increase in acceleration/ decrease in velocity = decelleration
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How is acceleration written?
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5 m/s/s or 5
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When does centripetal acceleration occur?
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When an object is in a circular motion.
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Define force.
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Push or pull with a certain size or direction. Measured in newtons(N) because its a force. Motion = unbalanced force
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What relationship do force and acceleration have?
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Changes/starts acceleration by changing an object's speed or direction
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What is net force?
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Combination of all forces acting upon an object. Net Force needs to be greater than 0N to put an object in motion
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Define Friction.
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A force that opposes motion between object in contact.
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Why does friction occur?
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Surfaces of objects have microscopic hills and valleys. When objects touch the hills and valleys "catch" each other.
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How are rough and smooth surfaces different?
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Rougher surfaces have greater friction due to greater size of hills and valleys.
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How is the amount of friction determined?
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by the amount of force pushing on the objects' surfaces
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What are the two types of friction?
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Kinetic and static friction
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What is kinetic friction?
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Friction between moving surfaces. (Sliding>Rolling)
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What is static friction?
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Force applied but object doesn't move because the force applied is equal to the force of the other surface.
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How do static and kinetic friction relate.
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Static friction is greater than kinetic friction. Static friction can become kinetic. kinetic can become static.
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How can friction be reduced?
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Use rolling instead of sliding friction.
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How can friction be increased?
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Rougher surfaces.
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Define gravity.
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Force of attraction between objects due to mass
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How can gravity change an object's motion?
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By changing speed/direction
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How do gravity and mass relate?
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Gravity is the result of mass. Since all object's have mass, all object's exert a gravitational pull.
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How is gravitational pull determined?
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By mass and distance. Greater mass,smaller distance = bigger gravitational pull. Smaller mass, greater distance = lower gravitational pull.
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What happens when an object is lifted?
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The force exerted overcame gravity's pull.
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What is Newton's law of universal gravitation?
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Objects in the universe attract each other through a gravitational force determined by an object's distance.
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Define weight.
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Amount of force with which gravity pulls on an object. Since it's a force it's measured in newtons(N).
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How do mass and weight relate?
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Greater mass = greater gravity's pull on an object. Mass can't change, weight can.
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