1. Ch.4 Motion Graph (1) ( 運動圖表 ) 1

2. 2 4.1 Displacement-time Graph ( 位移 - 時間綫圖 ) time t displacement s 0 The displacement-time graph (s-t graph) of uniform motion is a straight line passing through the origin.

3. 3 time t displacement s 0 The slope of the s-t graph equals to the velocity of the object. velocity = slope of s-t graph

4. 4 time t displacement s 0 A B slope of A > slope of B velocity of A > velocity of B

5. 5

6. 6 s = 10 m

7. 7 (b) What is the time when the girl’s displacement is 20 m?

8. 8 t = 30 s

9. 9 (c) What is the slope of the graph?

10. 10 (c) What is the slope of the graph? slope = (20-0) ÷ (30-0) = 0.667 m s -1

11. 11 (d) What is the velocity of the girl? velocity = slope = 0.667 m s -1

12. 12 4.2 Velocity-time Graph ( 速度 - 時間綫圖 ) time t velocity v 0 The velocity-time graph (v-t graph) of uniform motion (constant velocity) is a horizontal line.

13. 13 velocity v time t 0 A B v1v1 v2v2 v 1 = velocity of object A v 2 = velocity of object B v 1 > v 2

14. 14 time t 0 v t velocity v Displacement = Area of v-t graph

15. 15

16. 16 velocity = 6 m s -1

17. 17 What is the displacement of the man at t = 40 s?

18. 18 What is the displacement of the man at t = 40 s? displacement = area = (6)(40) = 240 m

19. 19

20. 20 s = 0

21. 21 s = 0 s = 2 m

22. 22

23. 23 t = 5 s

24. 24 t = 5 s t = 7 s

25. 25 (c)What is the velocity of the dog when (i) t = 2 s and (ii) t = 6 s

26. 26 (c)What is the velocity of the dog when (i) t = 2 s and (ii) t = 6 s (i)v = 0 (ii)v = slope = (4-0) ÷ (8-4) = 1 m s -1

27. 27

28. 28 t = 0 to 4 s slope = 0

29. 29 t = 4 to 8 s slope = 1 ms -1

30. 30

31. 31 Homework: Assignment Book 1. Chapter 4: Motion Graph (1) Q.1 – Q.3 (p.14-17) 2. Deadline: 2009 - ___ - ____