Ch.3 Uniform Motion (勻速運動) 1 2 3 4 forward

3.1 Uniform Motion (勻速運動) What is difference between average velocity (均速) and uniform velocity (勻速) ?

average velocity (均速) uniform velocity (勻速) 3.1 Uniform Motion (勻速運動) = displacement / time uniform velocity (勻速) = constant velocity = constant speed along a straight line

Class Exercise 3.1 State whether the apple is moving with uniform motion or not. Give reasons.

No. It is because the speed of the apple will increase. Class Exercise 3.1 State whether the apple is moving with uniform motion or not. Give reasons. No. It is because the speed of the apple will increase.

Class Exercise 3.1 State whether the car is moving with uniform motion or not. Give reasons.

No. It is because the motion is not a straight line. Class Exercise 3.1 State whether the car is moving with uniform motion or not. Give reasons. No. It is because the motion is not a straight line.

3.1 Uniform Motion (勻速運動) velocity = displacement ÷ time (v = s ÷ t) displacement = velocity × time (s = v × t) time = displacement ÷ velocity (t = s ÷ v)

Displacement (m) Time Taken (s) Velocity (ms-1) 200 40 ( a ) ( b ) 50 Class Exercise 3.2 Complete the table: Displacement (m) Time Taken (s) Velocity (ms-1) 200 40 ( a ) ( b ) 50 6 600 ( c ) 12

Complete the table: Displacement (m) Time Taken (s) Velocity (ms-1) Class Exercise 3.2 Complete the table: Displacement (m) Time Taken (s) Velocity (ms-1) 200 40 ( a ) (a) v = s ÷ t = 200 ÷ 40 = 5 m s-1

Displacement (m) Time Taken (s) Velocity (ms-1) ( b ) 50 6 Class Exercise 3.2 Complete the table: Displacement (m) Time Taken (s) Velocity (ms-1) ( b ) 50 6

s = v × t = 6 × 50 = 300 m Displacement (m) Time Taken (s) Velocity Class Exercise 3.2 Complete the table: Displacement (m) Time Taken (s) Velocity (ms-1) ( b ) 50 6 s = v × t = 6 × 50 = 300 m

Displacement (m) Time Taken (s) Velocity (ms-1) 600 ( c ) 12 Class Exercise 3.2 Complete the table: Displacement (m) Time Taken (s) Velocity (ms-1) 600 ( c ) 12

t = s ÷ v = 600 ÷ 12 = 50 s Displacement (m) Time Taken (s) Velocity Class Exercise 3.2 Complete the table: Displacement (m) Time Taken (s) Velocity (ms-1) 600 ( c ) 12 t = s ÷ v = 600 ÷ 12 = 50 s

Class Exercise 3.3

x1 = (v)(t) = (2)(10) = 20 m x2 = (v)(t) = (2)(10) = 20 m Class Exercise 3.3 x1 = (v)(t) = (2)(10) = 20 m x2 = (v)(t) = (2)(10) = 20 m x3 = (v)(t) = (2)(10) = 20 m

(b) What is the displacement of the car from t = 0 to (i) t = 10 s, (ii) t = 20 s, and (iii) t = 30 s.

(b) What is the displacement of the car from t = 0 to (i) t = 10 s, (ii) t = 20 s, and (iii) t = 30 s. (i) s = x1 = 20 m (ii) s = x1 + x2 = 40 m (iii) s = x1 + x2 + x3 = 60 m

Complete the following table. Time t / s 10 20 30 Displacement s / m

40 60 (c) Complete the following table. Time t / s 10 20 30 10 20 30 Displacement s / m 40 60 (d) From the data in (c), plot the graph of displacement against time.

time /s 10 20 30 20 40 60 × displacement / m

25 s

25 s s = 50 m

time /s 10 20 30 20 40 60 × displacement / m (30, 60) (0, 0)

25 s s = 50 m slope = (60 - 0) ÷ (30 - 0) = 2 m s-1

s = 50 m slope = (60 - 0) ÷ (30 - 0) = 2 m s-1 velocity of the car

Homework: Assignment Book 1. Chapter 3: Uniform Motion Q.1 – Q.2 (p.13) 2. Deadline: 2009 - ___ - ____