1. Back seat of an F-18
SPEED
http://alt.coxnewsweb.com/ajc/swf/blueangels/blueangels.swf

2. Question #8
• Is motion relative?
• Yes or No?
Are we ever really standing still?

3. Yes, All things are in motion.
• You may be perfectly still yet the earth is spinning on its axis
and orbiting the sun.
• The sun orbits the center of the
galaxy, our galaxy and
Andromeda are moving toward
one another, most of the other
galaxies are moving away.

4. So to measure motion in a meaningful way, we
measure it relative to the observer or another
object we consider not to be moving.
When you pass a car on the highway
moving in the same direction, you may
be going 70mph, and the other car
65mph. But your speed relative to the
other car is 5mph.
When the shuttle docks with the space station
the two orbiting objects approach one another
at a very slow speed relative to one another, but
both are orbiting at 17,000mph relative to the
surface of the earth.

5. Main IDEAS
•Motion is a change in position relative to your
surroundings.
•An object moves when it speeds up, slows
down or changes direction.

6. What’s a
Frame of
Reference?

8. A
B
C

9. BACKGROUND
OR OBJECT
USED FOR
COMPARISON

10. SPEED rate at w/c an
object moves
Distance (D)
Speed =
Time (T)

11. Another way to express this is in a “formula triangle” like this:
d
s t

12. SPEED IS….
Inversely Proportional to TIME
An ant crawled 12 inches
in 10 seconds. A second
ant crawled 24 inches in
10 seconds.
Compare the speed of the ants.

13. DIRECTLY PROPORTIONAL
TO DISTANCE
A plane flew 220 meters
in 1 second.
A second plane flew 220
meters in 2 seconds.
Compare their speeds.

14. DISTANCE
Length between two places
Distance = speed x time
D= ST
Expressed in km (1000m)

15. TIME
d
T
=
s

16. STEPS IN PROBLEM
SOLVING
 STEP 1. Write the formula
 STEP 2. Substitute given
numbers and units
 STEP 3. Solve for the
unknown.

17. CONSTANT SPEED
SPEED
THAT
DOES NOT
CHANGE

18. CONSTANT SPEED

19. SAMPLE PROBLEM:
At what speed did a plane
fly if it traveled 1760
meters in 8 seconds?

20. SOLUTION
Step 1. Speed = Distance/Time
Step 2. Speed = 1760 meters/ 8sec
Step 3. Speed = 220 m/sec

21. SAMPLE PROBLEMS:
1. A car travels 240 kilometers in
3 hours. What is the speed of the
car during that time?
ANSWER: S= d/t S= 240 km/3 hr
80 Km/Hr

22. The speed of a
cruise ship is 50
km/hr. How far will
the ship travel in
14 hours?
Answer: D = ST 700 km

23. AVERAGE SPEED
TOTAL DISTANCE / TOTAL TIME
AVERAGE total distance traveled
=
SPEED time

24. AVERAGE SPEED

25. A car travels 200 m in
10 seconds. What is
the average speed of
the car?
ANSWER: Ave speed= total d/total time
= 200m/10s
20 m/s

26. Definitions:
A change in position in a certain amount of time is __________.
__________________ is the rate at which an object moves and is
determined by dividing ____________ by _____________.
_________________________ is speed that does not change.
_________________________ is calculated by dividing the total
distance by the total time.

27. Image source: http://www.myteacherpages.com/

28. http://www.youtube.c
om/watch?v=arD374
MFk4w&feature=playe
r_embedded
http://www.youtube.co
m/watch?v=crjU5hu2fa
g&feature=player_emb
edded

29. SPEED
WORKSHEET
Complete for homework

30. Ken goes for a walk
2. Describe the motion
10
shown in the graph:
9
8 3.Calculate the average
Distance (km)
7
6 speed for the graph –
5 how does this value
4
3 compare to your
2 calculations above?
1
0
20 40 60 80 100 120 4. How far would Ken
Time (minutes) travel if he walked for
another hour (60
minutes)?
1.Calculate the speed at each point on the y-axis
Time (min) 20 40 60 80 100 120
Distance
(km)
Speed
(km/min)

31. Ken goes for a walk 2. Describe the motion
shown in the graph:
10
9
8 3.Calculate the average
Distance (km)
7 speed for the graph –
6
5
how does this value
4 compare to your
3
2
calculations above?
1 0.075 km/min
0
20 40 60 80 100 120
3. How far would Ken
Time (minutes)
travel if he walked for
another hour (60
1.Calculate the speed at each point on the y-axis minutes)? 13.5 km
Time (min) 20 40 60 80 100 120
Distance 1.5 3 4.5 6 7.5 9
(km)
Speed 0.075 0.075 0.075 0.075 0.075 0.075
(km/min)

32. Michelle Goes on a Bike Ride
5.Describe the motion shown in the
80
70
graph
60
Distance (km)
50
40
6.How many different rates are shown?
30 Label them using A, B, . . . . .
20
10
0
1 2 3 4 5 6
Time (hours)
7. Calculate the speeds for the different segments of the journey (Hint - you will have to use change in distance!)
Time A B C D
(hours)
Distance
(km)
Speed
(min/km)
8. What is the average speed for the entire trip? How does the value compare
to your calculations above?
9. Can you predict how far Michelle will travel if she travels for another 2
hours? Why or why not? What additional information do you need?

33. Michelle Goes on a Bike Ride
5.Describe the motion shown in the
80
70
graph (moving at varying speed)
60
Distance (km)
50
40
6.How many different rates are shown?
30 Label them using A, B, . . . . .
20
10
0
1 2 3 4 5 6
Time (hours)
7. Calculate the speeds for the different segments of the journey (Hint - you will have to use change in distance!)
Time (hours) A (1 h) B (1h) C (2 h) D (1h)
Distance (km)
10 0 40 10
Speed (km/h)
10 0 20 10
8. What is the average speed for the entire trip? How does the value compare
to your calculations above? 11.7 or 12 km/h
9. Can you predict how far Michelle will travel if she travels for another 2
hours? Why or why not? What additional information do you need?