# physical science chp. 13

## Terms

undefined, object
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kinematics
the branch of mechanics that describes how things move
inertia
the property of matter that causes objects to resist change in the state of motion
displacement
a change in position of an object
weight
the measure of the force of gravity on an object
scalar
quantities that express magnitude only
terminal velocity
the limit of the velocity at which an object can fall through a gas or a liquid
action-at-a-distance forces
forces that act on an object without touching it
vectors
quanitities that express magnitude and direction
speed
the rate at which an object changes position
mechanics
the study of motion
magnitude
as a part of velocity which describes size and direction
average speed
distance divided by time equals speed or velocity

V = d/t
acceleration
the rate at which velocity increases in a given amount of time
frame of reference
A system of reference points from which the position and motion of an object can be determined
action-reaction principle
Newton's third law of motion- For every action there is an equal and opposite reaction
geostationary orbit
when a satellite orbits at the same period as the surface of the earth below
dynamics
the branch of mechanics that describes why things
velocity (V)
the rate at which an object changes position in a specified direction
Universal Law of Gravitation
gravitational forces are directly related to the mass of an object
satellites
celestial bodies in orbit around another celestial body