# Physical Science – Chapter 11 "Motion"

motion
the change in position of an object when compared to a frame of reference
frame of reference
usually a stationary object, needed to describe motion
distance
the length of a path between two points
meter
SI unit for distance
vector
a quantity that has both magnitude (amount) and direction
vector
_ in the same direction are added, _ in opposite directions are subtracted
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resultant vector
the sum of 2 or more vectors
speed
the ratio of distance an object moves compared to the time elapsed
instantaneous speed
speed at any given moment
average speed
total distance divided by total time (V=d/t)
constant speed
speed that does not vary over time
distance-time graph
the slope of a line on this type of graph is speed
velocity
the speed and the direction an object is moving, a change in this can occur from a change in speed, direction, or both
acceleration
the rate of change in the velocity of an object, a vector
deceleration
negative acceleration
formula for acceleration
a=(Vf – Vi) / t