1. Ch.1 Distance (距離) & Displacement (位移)
Tai Wai Station
Kowloon Tong Station
displacement 4 km to the north
distance 4.4 km

2. Class Exercise 1.1
Distance travelled = ?

3. Class Exercise 1.1
Distance travelled = = 180 m

4. Displacement (位移) = change in position
The change in position is a straight line joining the start position (起點) and the end position (終點).
Magnitude (量值): Length of the straight line joining the start position and the end position.
Direction (方向): Direction of the straight line from the start position to the end position.

5. North (北)
West (西)
East (東)
South (南)

6. N
40°
Direction = ?

7. N
40°
50 ° E
Direction = 050° (or N 50° E)

8. N
60°
Direction = ?

9. N
90° + 60° = 150° E
60° S
Direction = 150° (or S 30° E)

10. N
40°
Direction = ?

11. N
90° + 90° + 50° = 230 ° W
40°
50° S
Direction = 230° (or S 50° W)

12. N
40°
Direction = ?

13. N
40° W
270° + 50° = 320°
Direction = 320° (or N 40° W)

14. Magnitude of displacement = ? Direction of displacement = ?
Class Exercise 1.2
Magnitude of displacement = ?
Direction of displacement = ?

15. Magnitude of displacement = 128 m
Class Exercise 1.2
Magnitude of displacement = 128 m
Direction of displacement = 180º + 40° = 220° (S 40º W)

16. Class Exercise 1.3 (a) & (b)

17. Class Exercise 1.3 (a) & (b)
6 m
6 m
East (90°)
East

18. Class Exercise 1.3 (c) & (d)

19. Class Exercise 1.3 (c) & (d)
6 m
6 m
East
East

20. Note: If the starting position and the end position are the same, the displacement is the same.

21. Class Exercise 1.4 (a)
You walk from LPSMC to the Entrance C of the Tsuen Wan MTR station. Find the magnitude and direction of your displacement.

22. Class Exercise 1.4 (a)
6.0 cm
3.1 cm
Magnitude = ?
Direction = ?

23. Direction = 180° + 78° = 258° (S 78° W)
Class Exercise 1.4 (a)
6.0 cm
78°
3.1 cm
Magnitude = (6.0 ÷ 3.1 ) × 100 = 194 m
Direction = 180° + 78° = 258° (S 78° W)

24. Class Exercise 1.4 (b)
You meet your friend, Tommy, at Entrance C. He is going to the YMCA in Luk Yeung Sun Chuen. What is his displacement from Entrance C to the YMCA?

25. Class Exercise 1.4 (b)
3.5 cm
Magnitude = ?
Direction = ?
3.1 cm

26. (N 50° E) Magnitude = 3.5 cm (3.5 ÷ 3.1 ) × 100 = 113 m 50°
Class Exercise 1.4 (b)
Magnitude =
(3.5 ÷ 3.1 ) × 100 = 113 m
Direction = 50°
(N 50° E)
3.5 cm
50°
3.1 cm

27. (a) In the space below, draw arrows to represent these displacements.
Class Exercise 1.5
Mr. Chan walks 3 m from A to the East. He turns 90 and walks 6 m to the South. Finally he walks a further distance of 9 m to the West.
(a) In the space below, draw arrows to represent these displacements.
(Use 1 cm to represent 1 m.)

28. Class Exercise 1.5 (a)

29. Class Exercise 1.5 (a)

30. (b) direction and magnitude of the total displacement = ?
Class Exercise 1.5 (b)
(b) direction and magnitude of the total displacement = ?

31. Class Exercise 1.5 (b)
45°
magnitude of the total displacement = 8.5 m
direction of the total displacement = 180° + 45° = 225° (SW)

32. Class Exercise 1.6 (a)

33. Class Exercise 1.6 (a)
East
12 m 33

34. Class Exercise 1.6 (a)
East
12 m
East
6 m 34

35. Class Exercise 1.6 (a)
East
12 m
East
6 m
18 m
East

36. Class Exercise 1.6 (b)

37. Class Exercise 1.6 (b) S 37

38. Class Exercise 1.6 (b) S
-10 m or 10 m (West)

39. Class Exercise 1.6 (b) S
-10 m or 10 m (West)
8 m (East) 39

40. Class Exercise 1.6 (b) S
-10 m or 10 m (West)
8 m (East)
28 m 40

41. Class Exercise 1.7

42. Class Exercise 1.7
distance = = 7 m

43. Class Exercise 1.7
distance = = 7 m 43

44. Class Exercise 1.7

45. magnitude = m tan a = ¾ a = 36.9° direction = 127° (S 53° E)
Class Exercise 1.7 a
magnitude =
tan a = ¾ a = 36.9° direction = 127°
(S 53° E) m

46. Class Exercise 1.7

47. Class Exercise 1.7 P

48. Class Exercise 1.7 P
-4.0 m or m (West)
3.0 m (South)

49. Scalar (無向量) Vector (向量/矢量)
1.3 Scalar and Vector
Scalar (無向量)
Vector (向量/矢量)
has magnitude (量值) only.
has both magnitude and direction.
Example:
distance (距離)
time (時間)
temperature (溫度)
speed (速率)
volume (體積)
displacement (位移)
velocity (速度)
acceleration (加速度)
force (力) …