Chapter3x

taupeselectionMechanics

Nov 14, 2013 (3 years and 10 months ago)

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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


at
2

Velocity, position,
acceleration

v
f
2

=
v
i
2

+ 2
a
d