1. MOTION
Unit 9, Chapter 11

2. I. Describing Motion Earth Frame of reference: what motion
is compared against.
B. Motion is relative or dependant on the
frame of reference. (Einstein)
The most common frame of
Reference is the Earth.
Earth
The car moves left in reference to the…

3. Now lets get tricky! The corvette will be going forward and backward!
- forward in relation to the Earth
- backward in relation to the Indy car

4. Distance and displacement
II. Measuring Motion
A. Distance: the length of a path between
two points.
B. Direction- relative to a F.O.R.
C. Time needed to complete the motion.
The above items are known as:
scalars
They have magnitude only.

5. D. Displacement: The distance and
direction from the starting point, to the
ending point in a straight line (“As the
crow flies”)
Go to map.

6. III. Vectors Are arrows that show magnitude and direction.
4 miles
2 miles
Displacement can be displayed as a
vector.
C. Vectors can be combined.
Like this
4 miles
2 miles + =
2 miles +
4 miles =

7. Pythagorean
Or this

8. IV. Speed A. What are some examples of speed?
B. Speed is measured by the distance
traveled in a certain amount of time.
C. Calculated as:
D. Units: mi/hr, m/s, km/hr (a scalar)
Speed = Distance = d
Time t

9. V. Instantaneous Speed A. Your speed the moment you look down at
the speedometer.
B. Calculated by: speed (V ) = distance (d)
time (t)
C. Example:

10. VI. Average Speed A. Calculated by: avg. speed = total distance
Instantaneous speed
VI. Average Speed
A. Calculated by:
avg. speed = total distance
total time
B. Symbol Equation:

11. C. Example: What is the avg. speed if a car travels 2
Instantaneous speed
C. Example: What is the avg. speed if a car travels 2
miles in 4 minutes, stops for 1 minute and travels 3
miles in 3 minutes?

12. VII. Velocity Velocity is speed with an indicated direction.
Examples: 65 mi/hr North, 12 m/s Up
Indicated by the use of a “Vector”
10 meters / second
The arrow = direction
Magnitude (length) tells “how much”
“10 meters/second”

13. VIII. Acceleration A. Acceleration is any change in velocity.
B. Acceleration is any change in speed or
direction.
C. We calculate acceleration with the
following equation:
Acceleration =
Final Velocity – Initial Velocity
Change in Time

14. Acceleration example
D. Example: A car traveling at 30 mi/hr
increases speed to 60 mi/hr in 6 sec.
What is the car’s acceleration?
vf = 60 mi/hr
a = = Dv Dt
vf - vi t
vi = 30 mi/hr
t = 6 sec
a = =
60 mi/hr – 30 mi/hr
6 sec
30 mi/hr
6 sec
= 5 mi/hr/s
What does this answer mean?
For each second that passes the car is traveling 5 mi/hr faster than before.

15. Acceleration continued
E. A positive acceleration means
speeding up.
F. A negative acceleration means
slowing down.
G. Acceleration can be expressed as a
vector since it includes direction.