Kinematics
•
Kinematics
is the branch of physics that
describes the motion of points, bodies
(objects) and systems of bodies (groups of
objects) without consideration of the causes
of motion.
Kinematics
•
One

dimensional kinematics. Movement
along one axis.
•
Distance
–
the total distance traveled from
beginning to end. It always has a positive
value
. A scalar quantity
–
completely
characterized only by magnitude.
•
Displacement
–
the change in position
. A
vector quantity completely characterized by
magnitude and direction.
Kinematics
•
Average speed
–
distance
divided
by elapsed
time
.
•
Average velocity
–
displacement divided by
elapsed time
.
•
Some units for speed and velocity are
and any unit of length divided by a unit of
time.
,,
m km mi
s h h
Kinematics
•
Instantaneous speed
–
the speed at a given
instant.
•
Instantaneous
velocity
–
the velocity at a given
instant.
Kinematics
•
Average acceleration
–
the change in velocity
divided but
the
change in time.
f i
av
f i
v v
v
a
t t t
Kinematics
•
Instantaneous acceleration
–
the acceleration
at a given instant.
Kinematics
•
Constant acceleration
–
when acceleration is
constant, instantaneous acceleration is equal
to the average acceleration.
•
In this course
we will
only be dealing with
situations involving constant acceleration.
Kinematics
•
In the following slide the subscript
i
refers to
an initial
condition
, and the subscript
f
refers
to
a final condition.
Table 2

4
Constant

Acceleration Equations of Motion
Variables Related
Equation
Velocity, time,
acceleration
v
f
=
v
i
+
at
Initial, final, and
average velocity
v
av
= ½(
v
f
+
v
i
)
Position, time,
velocity
d
= ½(
v
f
+
v
i
)
t
Position, time,
acceleration
d
=
v
i
t
+½
at
2
Velocity, position,
acceleration
v
f
2
=
v
i
2
+ 2
a
d
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