the Physics Classroom Summarized2
Kinematics
Much of the following has been taken directly from the Physics Classroom website and the Physics
Classroom Summarized-Kinematics, although there are some differences.
Scalars and Vectors
 scalars: described by magnitude (or size)
 vectors: described by both magnitude and direction
Distance and Displacement
 distance: scalar, how far an object has travelled
 displacement: vector, change in position
Speed and Velocity
 speed: scalar, refers to how fast an object is moving
 velocity: vector, refers to rate at which an object changes its position
average speed =
distance d
=
time
t
average velocity =
displacement d
=
time
t


Instantaneous Speed - the speed at any given instant in time.
Average Speed - found with distance/time ratio.


Instantaneous Velocity - the velocity at any given instant in time.
Average Velocity - found with displacement/time ratio.
Acceleration
 vector
 rate at which an object changes its velocity
 constant acceleration if velocity is changing by same amount each second
 common units: m/s/s or m/s2
acceleration 
change in velocity v v f  vi


time
t
t
Ticker Tape Diagrams
 a long tape is attached to a moving object
 a ticker places a tick upon the tape at regular intervals of time - say every 0.10 second
Last updated August 27, 2014
1.
The Meaning of Shape for a p-t Graph
 if velocity is constant, then slope is constant (i.e., a straight line)
 if velocity is changing, then slope is changing (i.e., a curved line)
 if the velocity is positive, then slope is positive (i.e., moving upwards and to the right).
See Animations of Various Motions with Accompanying Graphs
The Meaning of Slope for a p-t Graph
 slope of a position-time graph is velocity of the object
The Meaning of Shape for a v-t Graph
 if acceleration is zero, then slope is zero (i.e., a horizontal line)
 if acceleration is positive, then slope is positive (i.e., an upward sloping line)
See Animations of Various Motions with Accompanying Graphs
Determining the Area on a v-t Graph
 area bounded by line on graph and time axis of a velocity-time graph gives the displacement
Introduction to Free Fall
 object that is being acted upon only by the force of gravity
 air resistance is ignored
 on Earth, accelerate downwards at a rate of 9.81 m/s/s, (often approximated as 10 m/s/s)
The Acceleration of Gravity
 special symbol to denote it - the symbol g
 even on Earth, there are local variations
The Kinematic Equations
 used for constant velocity or constant acceleration motion
v vf  vi

t
t
v f  vi  at
a
1
d  (vi  v f )t
2
1
d  vi t  at 2
2
2
2
v f  vi  2ad
Kinematic Equations and Problem-Solving
 when appropriate, construct diagram
 when appropriate, state positive direction
 identify and list given information
 identify unknown with a question mark
 identify and list equation that will be used
 substitute into equation and use algebraic steps to solve
 check: answer to insure it is reasonable, significant figures, units, and direction if necessary
Last updated August 27, 2014
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