Ch.1 Distance (Ch.1 Distance ( 距離距離 ) & Displacement () & Displacement ( 位位移移 ))
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Tai Wai Station
Kowloon Tong Station
displacement 4 km to the northdistance
4.4 km
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Class Exercise 1.1
Distance travelled = ?
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Class Exercise 1.1
Distance travelled = 12 + 98 + 70 = 180 m
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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.
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North ( 北 )
West ( 西 )
East ( 東 )
South ( 南 )
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N
40°
Direction = ?
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N
40°
Direction = 50°
50 °
E
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N
60°
Direction = ?
9
N
60°
Direction = 150°
S
E
90° + 60° = 150°
10
N
40°
Direction = ?
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N
40°
Direction = 230 °
S
W
50°
90° + 90° + 50° = 230 °
12
N
40°
Direction = ?
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N
40°
Direction = 320°
W270° + 50° = 320°
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Class Exercise 1.2
Magnitude of displacement = ?Direction of displacement = ?
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Class Exercise 1.2
Magnitude of displacement = 128 mDirection of displacement = 180º + 40° = 220°
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Class Exercise 1.3 (a) & (b)
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Class Exercise 1.3 (a) & (b)
6 m
East (90°)
6 m
East
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Class Exercise 1.3 (c) & (d)
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Class Exercise 1.3 (c) & (d)
6 m 6 m
East East
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Note: If the starting position and the end position are the same, the displacement is the same.
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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.
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Class Exercise 1.4 (a)
6.2 cm
3.2 cm
Magnitude = ?Direction = ?
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Class Exercise 1.4 (a)
6.2 cm
3.2 cm
Magnitude = (6.2 ÷ 3.2 ) × 100 = 194 mDirection = 180° + 77° = 257° (S 77 W)
78°
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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?
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Class Exercise 1.4 (b)
3.2 cm
Magnitude = ?Direction = ?
3.7 cm
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Class Exercise 1.4 (b)
3.2 cm
Magnitude = (3.7 ÷ 3.2 ) × 100 = 116 m
Direction = 50° (N 50 E)
3.7 cm
50°
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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.)
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Class Exercise 1.5 (a)
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Class Exercise 1.5 (a)
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Class Exercise 1.5 (b)
(b) direction and magnitude of the total displacement = ?
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Class Exercise 1.5 (b)
magnitude of the total displacement = 8.5 mdirection of the total displacement = 180° + 45° = 225°
45°
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Class Exercise 1.6 (a)
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Class Exercise 1.6 (a)
12 m East
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Class Exercise 1.6 (a)
12 m
6 m
East
East
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Class Exercise 1.6 (a)
12 m
6 m
18 m
East
East
East
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Class Exercise 1.6 (b)
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Class Exercise 1.6 (b)
S
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Class Exercise 1.6 (b)
-10 m or 10 m (West)
S
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Class Exercise 1.6 (b)
-10 m or 10 m (West)
8 m (East)
S
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Class Exercise 1.6 (b)
-10 m or 10 m (West)
8 m (East)
28 m
S
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Class Exercise 1.7
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Class Exercise 1.7
distance = 3 + 4 = 7 m
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Class Exercise 1.7
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Class Exercise 1.7
53°
magnitude = 534 22
direction = 90° + 37° = 127° (S 53 E)
m
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Class Exercise 1.7
62°
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Class Exercise 1.7
62°
P
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Class Exercise 1.7
-4.0 m or 4.0 m (West)
3.0 m (South)
62°
P
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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 )• ……
Example:• displacement (位移 )• velocity (速度 )• acceleration (加速度 )• force ( 力 )• ……
1.3 Scalar and Vector
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Homework: Assignment Book 1. Chapter 1: Distance & Displacement
Q.1 – Q.6 (p.1-5) 2. Deadline: 2011 - - ____