19 terms

# Chapter 13 Forces

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Force
a push or pull causing an object to start or stop moving or change its motion
Friction
the force that opposes the motion of an object
Sliding Friction
when two solid surfaces slide over eachother
Rolling Friction
when an object rolls over a surface
Fluid Friction
when an object moves through a fluid
Lubricant
substances that enable sliding friction to change to fluid friction
Balanced Forces
forces that are opposite in direction and equal in size (no change in motion)
Unbalanced Forces
forces that are not opposite in direction and equal in size (one force is greater than the other=change in motion)
Inertia
tendency of objects to remain in motion or stay at rest
First Law of Motion
on object at rest will stay at rest and an object in motion will remain in motion unless acted upon by an unbalanced force
Second Law of Motion
relationship between force, mass and acceleration (force=mass x acceleration)
Third Law of Motion
for every action there is an equal and opposite reaction
Gravity
the attractive force between all objects in the universe
9.8m/s/s
acceleration rate due to gravity
Projectile Motion
always a curve, the path a projectile takes when thrown into the air (forward due to inertia and downward due to gravity)
Orbital Motion
An object that orbits another object
Law of Universal Gravitation
all objects in the universe attract each other by the force of gravity
Weight
the measure of the force of gravity on a mass, measured in Newtons (weight may vary)
Mass
the amount of matter that makes up an object (this remains constant)