Motion and Energy
Ch.9
9.1 Describing Motion
Essential Questions

What is motion?

What is the difference between distance
and displacement?
I. Describing Motion
a. Motion
 When
an object changes position
over time when compared with a
reference point.
b. Reference Point

Place or object used for
comparison to determine
if something is in motion
Reference Point
A.If you are sitting in a car that is moving, would you
say that your seat moved?
B.What does your answer depend on?
C.Name two things that the people on the street
corner would say are in motion?
D.Name two things that the driver of the car would
say appear to be in motion?
E. If you are seated on the train: Who or what would
be moving compared to you? What would be still
compared to you?
F. If you are the man standing on the platform: Who
or what would be moving compared to you? What
would be still compared to you?
G. Summarize the meaning of “Relative Motion”.
c. Distance & Displacement

Distance -Total
length of the actual
path between 2
points (yellow path)

Displacement length & direction of
a straight line
between starting &
ending points
9.2 Speed and Velocity
Essential Questions

How do you calculate speed?

How can you describe a change in
velocity?
II. Speed and velocity
a. Speed - The rate at
which an object
moves
b. Average Speed =
Distance
Time
S=d
t
c. Velocity - the speed
of an object in a
particular direction
(or reference point).
d. Velocity changes if
either speed or
direction changes
e. Graphing speed - you can show
motion with a line graph by plotting
distance versus time.
- Time- x axis (horizontal axis)
- Distance - y axis (vertical axis)
f. Speed = Slope
(the steepness of the line)
1. How far did the jogger run in 5 min?
2. Between what minutes did the jogger stop running?
3. Between what minutes did the jogger run the fastest?
9.3 Acceleration
Essential Questions

What kind of motion does acceleration
refer to?

How do you calculate acceleration?
III. Acceleration
a. A change in velocity
b. If speed changes or direction changes,
you have acceleration
c. Negative acceleration (slowing down) is
also called deceleration
d. Acceleration is
final velocity minus
initial velocity
divided by the time
it takes to change
velocity.

Acceleration =
Vf – Vi
Time
e. Acceleration is the rate at which velocity
changes.
f. It tells you how fast velocity changes
g. Graphing acceleration
- you can use both a
speed versus time
graph and a distance
versus time graph to
analyze acceleration
What is the acceleration
of the cyclist?
 Is he accelerating at a
constant rate or not?
 How do you know?

8. Graphing Acceleration

What is the speed of the
cyclist between the 2nd
and 3rd second?

What is the speed of the
cyclist between the 5th
and 6th second?

Is the cyclist accelerating
or not?

How do you know?
9.4 Energy
Essential Questions

What factors affect an object’s kinetic
energy and potential energy?

What is the law of conservation of energy?
IV. Energy
a.
b.
Work – is done when an
object is caused to move a
certain distance.
The ability to do work or
cause change is called
energy.
c. Kinetic energy – the energy an
object has due to its motion.
i
Kinetic energy of an object
depends on both its mass and
speed.
d. Potential energy – stored energy
that results from the position or
shape of an object.
e. Gravitational potential energy –
an objects energy which depends
on its weight and its height
relative to a reference point.
f. Elastic potential energy – the
potential energy of objects that
can be stretched or compressed.
g. Mechanical energy – an
object’s combined kinetic
energy and potential energy.
h. Any object that rises or falls
experiences a change in its
kinetic and gravitational
potential energy.
i.
Law of conservation of
energy – energy cannot be
created or destroyed.