1. Chapter 11: MotionChapter 11: Motion
Section 1: Describing Motion

2. MotionMotion
Motion occurs
when:
◦ an object moves a
certain distance in
a certain amount
of time
◦ an object’s
position changes

3. DistanceDistance
Distance is how far something has moved
Measured in METERS, km, cm, mm, etc.

4. DisplacementDisplacement
Displacement is the
change in position of
an object
Also measured in
METERS, km, cm,
mm, etc.

5. SpeedSpeed
Speed is the
distance an
object travels
over the amount
of time it takes to
travel
Measured in m/s (meters per second)
Speed (m/s) = distance (m) ÷ time (s)

6. Calculating SpeedCalculating Speed
1. After driving for exactly 60 seconds, you
have driven 600 meters. What speed
were you driving?
2. After driving for 1 hour, you have driven
72 kilometers. What speed were you
driving?
a. Calculate the speed in km/hr
b. Calculate the speed in m/s

7. Constant & Changing SpeedConstant & Changing Speed
Constant speed means an object does not
speed up or slow down.
Changing speed means an object gets
faster or slower.

8. Average SpeedAverage Speed
 We usually calculate the average speed:
Average speed (m/s) = total distance (m) ÷ total
time (s)
Yesterday, John Doe ran 6 km in 30 minutes.
Sometimes he sped up and sometimes he
slowed down. What was his average speed?
a. Convert 6km to m: 6km x 1000m/1km = 6000 m
b. Convert 30 mins to sec: 30 min x 60sec/1min =
1800 sec
c. Calculate avg. speed: 6000 m ÷ 1800 sec =
3.33m/s

9. Instantaneous SpeedInstantaneous Speed
Speed can be
measured at a
certain point in
time.
For instance, if
you are driving,
your speedometer
may read 30
mi/hr.
You don’t have to drive
for an hour for your car
to know this – your
speed is instantaneous.

10. Graphing SpeedGraphing Speed
Distance and Time
are variables!
◦ Independent
Variable: time
◦ Dependent Variable:
distance

11. Graphing Constant SpeedGraphing Constant Speed

12. Graphing Changing SpeedGraphing Changing Speed

13. Graphing Changing SpeedGraphing Changing Speed

14. Graphing Changing SpeedGraphing Changing Speed

15. VelocityVelocity
Velocity is a measure of an object’s
SPEED and DIRECTION.
Velocity is measured by:
velocity = displacement ÷ time
v = d/t

16. Velocity & DisplacementVelocity & Displacement
If you run around a
circular track and
end up in the same
position you started,
your displacement is
0.
So is your velocity: v
= 0/time, so v=0

17. Calculating VelocityCalculating Velocity
1. You walk down a winding road and end
up 80 meters from your starting point.
It took 1 minute and 20 seconds to walk
from one end to the other. What was
your velocity?
2. Was your speed greater or less than the
velocity you calculated in #1?