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Physics Lab 1
Graph Matching
Eleanor Roosevelt High School
Chin-Sung Lin
Kinematics
Kinematics is a branch of mechanics. It is the science of describing the motion of objects using words, diagrams, numbers, graphs, and equations.
The goal of kinematics is to develop models to describe the motion of real-world objects.
Distance & Displacement
Scalars & Vectors
Scalars are quantities that are fully described by a magnitude (or numerical value) alone.
Vectors are quantities that are fully described by both a magnitude and a direction.
Distance & Displacement
Distance is a scalar quantity that refers to "how much ground an object has covered" during its motion.
Displacement is a vector quantity that refers to "how far out of place an object is"; it is the object's overall change in position.
Distance:10 m
Displacement:10 m East
10 m
Distance & Displacement
Distance/Position
t
d
Distance/Position
t
d
Distance/Position
t
d
Speed & Velocity
Speed
A speed (v) is a scalar quantity
Distance (d) covered per unit of time (t). Speed is a measure of how fast something is moving. It is the rate at which distance is covered
v = d / tUnit: meters per second (m/s), miles per hour
(mi/h), kilometers per hour (km/h)
Velocity
A velocity (v) is a vector quantity
Velocity is the measurement of the rate and direction of change in the displacement (d) of an object
v = d / tThe speed is the magnitude of velocity
Unit: meters per second (m/s), miles per hour (mi/h), kilometers per hour (km/h)
Speed & Velocity
Speed has only magnitude
Velocity has magnitude and direction
Speed/Velocity
t
v
Speed/Velocity
t
v
Speed/Velocity
t
v
Speed/Velocity
Speed: the slope of the distance-time (d-t) graph
t
d
slope = v (speed)
Acceleration
Acceleration
An acceleration (a) is a vector quantity
acceleration is the rate of change of velocity with time
a = Δv / t
a = acceleration (m/s2)
v = change of velocity (m/s)
t = time interval (s)
Acceleration
An acceleration (a) is also a scalar quantity
When linear (straight-line) motion is considered, it is common to use speed and velocity interchangeably and the acceleration may be expressed as the rate at which speed changes
a = Δv / t
a = acceleration (m/s2)
v = change of speed (m/s)
t = time interval (s)
Acceleration
t
a
Acceleration
t
a
Acceleration
Acceleration: the slope of the speed-time (v-t) graph
t
v
slope = ax (acceleration)
Distance, Speed & Acceleration
d-t
t
v
slope = ax
t
a
slope = 0
ax
t
d slope = increasing at constant rate
v-t a-t
The End