# 8th grade Science MOTION AND FORCE STUDY GUIDE

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to describe velocity you need to know
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speed and direction
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according to Newton’s second law of motion
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an object acted on by a force will accelerate in the direction of the force; F=m*a
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the distance traveled divided by the time taken to travel the distance is
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speed
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the statement \”for every action, there is an equal but opposite reaction\” is a statement of
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Newton’s 3rd Law
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inertia is
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the tendency of an object to resist a change in motion and is dependent on the mass of the object
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acceleration is a change in
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speed or direction. either speed up, slow down, or change direction
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momentum is a measure of
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how hard it is to stop an object; momentum=m*v
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whenever a body is in motion
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there is always friction to oppose the motion
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if gravity did not affect the path of a horizontally thrown ball, the ball would
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continue in a straight path until acted on by another force
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the force you have to overcome to start an object moving is
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static friction
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when you graph the motion of an object
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you put time on the horizontal axis and distance on the vertical axis
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a feather falls through the air more slowly than a brick because of
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air resistance
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Newton’s first law of motion states that an object remains at rest unless
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an unbalanced force acts on it
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forces that are equal in size but opposite in direction are
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balanced
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air resistance increases
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as you move faster
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acceleration involves a change in
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velocity
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the relationship among force, mass, and acceleration is stated in
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Newton’s 2nd law
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speed is the rate of change in
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distance
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distance
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is a length traveled
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displacement
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is the difference between start and end points and direction
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speed
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is the distance traveled divided by the time taken to travel that distance
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velocity
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is speed and direction of an object
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positive acceleration
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means that the object is getting faster over time, or speeding up
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negative acceleration
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means that the object is slowing down

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