1. Motion
Part 1: Motion and Speed

2. Speed is the distance an object travels per unit of time.
To calculate speed:
Speed = Distance ÷ Time
Distance is in meters (m)
Time is in seconds (s)
Speed is in meters per second (m/s)

3. A snail takes 5.0 s to crawl across the ruler.
Example 1
A snail takes 5.0 s to crawl across the ruler.
Speed = 2.0 m/s
Speed = Distance ÷ Time
Speed = 0.07 m ÷ 5.0 s

4. A car drives 250 m in one minute.
Example 2
A car drives 250 m in one minute.
Speed = m/s
Speed = Distance ÷ Time
Speed = 250 m ÷ 60 s

5. Use the Formula Triangle!d
To calculate speed:
To calculate time:
To calculate distance:
s = d / t
t = d / s
d = s x t

6. Distance vs. Displacement
Distance and displacement are different.
Distance
How far an object moves in total.
Displacement
The distance and direction an object moves from a starting position.

7. Distance vs. Displacement
Jeffrey, my distance was 176 meters!
But Billy, your displacement was 1 meter!
BEGIN
END

8. Distance vs. Displacement
90 ft.
Distance = 90 ft.
Displacement = 90 ft.

9. Distance vs. Displacement
90 ft.
90 ft.
Distance = 180 ft.
Displacement =127 ft.

10. Distance vs. Displacement
90 ft.
90 ft.
90 ft.
Distance = 270 ft.
Displacement = 90 ft.

11. Distance vs. Displacement
90 ft.
90 ft.
90 ft.
90 ft.
Distance = 360 ft.
Displacement = 0 ft.

12. Any Questions?

13. Motion
Part 2: Distance-Time Graphs

14. Graphing Speed The motion of an object can be graphed.
A distance-time graph shows the motion of a certain object in line graph form.
Time is plotted on the horizontal (X) axis
Distance is plotted on the vertical (Y) axis

15. The slope of a distance-time graph is the speed
Distance-Time Graphs
The slope of a distance-time graph is the speed
Time (s)
Distance (m) 1 2 4 3 6 8 5 7 9 12 10 16

16. Distance-Time Graphs S = D ÷ T S = D ÷ T S = D ÷ T = 0 ÷ 4 = 0 m/s
= 8 ÷ 4
= 2 m/s
S = D ÷ T
= 8 ÷ 2
= 4 m/s

17. Distance-Time Graphs Constant speed No speed Constant speed
(moving away)
No speed
(standing still)
Constant speed
(moving closer)
(and faster!)

18. Interpreting a D-T Graph (1)
Analysis:
Time (s)
Distance (m)
The distance (m) stays the same as the time (s) increases
Therefore, the object is at rest (not moving)

19. Interpreting a D-T Graph (2)
Analysis:
The object is moving away from the reference point
The object is moving at a constant speed
The object is moving quickly
Time (s)
Distance (m)

20. Interpreting a D-T Graph (3)
Analysis:
The object is moving towards the reference point
The object is moving at a constant speed
The object is moving slowly
Time (s)
Distance (m)

21. Interpreting a D-T Graph (4)
Analysis:
In Part A, the object is moving away at a constant speed
In Part B, the object is at rest
In Part C, it is moving towards at constant speed
Time (s)
Distance (m) A B C

22. Any Questions?

23. Motion
Part 3: Velocity and Acceleration

24. Speed is the distance an object travels in a specific amount of time.
Review: Speed
Speed is the distance an object travels in a specific amount of time.
To calculate speed:
Speed = Distance ÷ Time
Distance is in meters (m)
Time is in seconds (s)
Speed is in meters per second (m/s)

25. Velocity Sometimes, knowing the speed isn’t enough.
For example, sailors must know the speed and direction their boat is travelling in.
Velocity is a description of both speed and direction.
e.g. a sailboat travelling at kph in a SE direction

26. Sometimes, knowing the speed isn’t enough.
Velocity
Sometimes, knowing the speed isn’t enough.
For example, sailors must know the speed and direction their boat is travelling in.
Velocity is an example of a vector, a quantity that has both magnitude and direction.

27. Acceleration Acceleration can be:
Objects can speed up, slow down or change direction.
Acceleration measures how much an object’s speed changes over a certain time.
Acceleration can be:
A change in speed
A change in direction
A change in speed & direction

28. Acceleration can be positive, negative or zero.
Positive Acceleration
Object speeds up
Negative Acceleration
Object slows down
Zero Acceleration
Constant or no speed

29. Acceleration a = Vfinal - Vinitial t Formula for acceleration:
acceleration = change in velocity
time
a = Vfinal - Vinitial t
Velocity: meters per seconds (m/s)
Time: seconds (s)
Acceleration: meters per second squared (m/s2)

30. Example 1 a = Vfinal - Vinitial t a = 20.0 m/s - 11.0 m/s 4.0
A motorcycle’s velocity at the top of the hill is 11.0 m/s. 4.0 seconds later it reaches the bottom of the hill with a velocity of 20.0 m/s. What is the acceleration of the motorcycle?
a = Vfinal - Vinitial t
a = m/s m/s
4.0
a = 9.0 m/s
4.0
a = m/s2

31. Example 2 a = Vfinal - Vinitial t - 2.9 m/s2 = 0.0 m/s - 13.0 m/s t
A speed skater just finished a race. After she crossed the finish line, she coasted to a complete stop. If her initial speed was 13.0 m/s and her acceleration was -2.9 m/s2, how long did it take her to stop?
a = Vfinal - Vinitial t
- 2.9 m/s2 = 0.0 m/s m/s t
t (- 2.9) = m/s
t = m/s /
t = 4.5 s

32. Any Questions?

33. Motion
Part 4: Speed-Time Graphs

34. Interpreting a D-T Graph (1)
Analysis:
Time (s)
Distance (m)
The distance (m) increasing as time (s) passes
The distance gets larger and larger with each second
This shows (+) acceleration

35. Interpreting a D-T Graph (1)
Analysis:
Time (s)
Distance (m)
The distance (m) decreasing as time (s) passes
The distance gets smaller & smaller with each second
This shows (-) acceleration

36. Interpreting a D-T Graph (3)
Analysis:
The distance (m) from a reference point is increasing
It is increasing at a regular rate
This shows (0) acceleration
Time (s)
Distance (m)

37. Interpreting a D-T Graph (3)
Analysis:
The object is moving towards the reference point
The object is moving at a constant speed
The object is moving slowly
Time (s)
Distance (m)

38. Interpreting a S-T Graph (4)
Analysis:
Time (s)
Speed (m/s)
The speed (m/s) is constant as time (s) passes
The object’s speed is not changing
This shows (0) acceleration

39. Interpreting a S-T Graph (5)
Analysis:
Time (s)
Speed (m/s)
The speed (m/s) is increasing as time (s) passes
The object speed is changing
This shows (+) acceleration

40. Any Questions?