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The science of describing the motion of
objects using words, diagrams, numbers,
graphs, and equations
SCALAR
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A numerical value with no
direction
Quantities that are fully
described by a magnitude
(or numerical value) alone
E.g. temperature, mass,
and energy
VECTOR
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A numerical value in a
specific direction
Quantities that are fully
described by both a
magnitude and a direction
Quantity
Category
5m
Scalar
30 m/s, East
Vector
5 mi., North
Vector
20 degrees Celsius
Scalar
256 bytes
Scalar
4000 calories
Scalar
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A scalar quantity
Refers to “how much ground an object has
covered” during its motion
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A vector quantity
Refers to “how far out of place an object is”; it
is the object’s overall change in position
A person walks 4 meters East, 2
meters South, 4 meters West,
and finally 2 meters North.
4 meters
Total distance = 12 meters
Total displacement = 0
Displacement, being a vector
quantity, must give attention to
direction. The 4 meters East
cancels the 4 meters West; and
the 2 meters South cancels the
2 meters North
2 meters
2 meters
4 meters
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What is the displacement of a cross-country
team if they begin at the school, run 10 miles
and finish back at the school?
 Answer: Displacement = 0; round-trip motions
always have a displacement of 0
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What is the distance and displacement of
race car drivers in the Indy 500?
 Distance = 500 miles
 Displacement = 0; they finish where they started
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A scalar quantity
Refers to “how fast an object is moving”
Rate at which an object covers distance
Measured in meters per second (m/s) or
kilometers per hour (km/h)
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A vector quantity
Refers to “the rate at which an object
changes its position”
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A vector quantity
Defined as the rate at which an object
changes its velocity
An object is accelerating if it is changing its
velocity