1. Motion of an object is described by its position ,

1. 1. Motion of an object is described by its position, speed, direction, and acceleration.

2. 2) MKS units areMeters, Kilograms Seconds

3. 3. Initial means “first” or “starting”

4. 4 . D =“delta”D means “the change in”5. D= final – initial

5. 6. wrt means “with respect to”

6. 7. fixed means constant, unchanging.

7. When is an object moving?

8. 4.1Motion Is Relative 8. An object is moving when its position changes relative to a fixed point.

9. Vectors and Scalars

10. 4.1Motion Is Relative 9 . Vectors or vector quantities have magnitude and direction • Scalars or scalar quantities have only magnitude

11. 11. Magnitude means size

12. 4.1Motion Is Relative 12.Distance means total path length an object travels 13.Displacement means final position minus initial position

13. 4.1Motion Is Relative 14. In symbols Displacement =Dxor Dy

14. Travel around perimeter:

15. Travel around perimeter: from A B

16. Travel around perimeter: from A BC

17. Travel around perimeter: from A BC D

18. Travel around perimeter: from A BCDA

19. Distance = path length =

20. Distance = path length =28 m

21. Distance = path length =28 m Displacment = 0

22. 15) Distance is a scalar and Displacement is a vector

23. 16. Motion is relative: we always describe motion relative to something else

24. 17. Usually we measure motion relative Earth’s surface

25. 4.1Motion Is Relative How can you tell if an object is moving?

26. http://www.youtube.com/watch?v=oRBchZLkQR0http://www.youtube.com/watch?v=KLd-rJMoekohttp://www.youtube.com/watch?v=xMF2CfYLomYhttp://www.youtube.com/watch?v=oRBchZLkQR0http://www.youtube.com/watch?v=KLd-rJMoekohttp://www.youtube.com/watch?v=xMF2CfYLomY

27. 4.2Speed 18. Speed = distance time v = d t

28. 4.2Speed 19. Before Galileo, people described motion as “slow” or “fast.”

29. 4.2Speed 20.Galileo was the first to calculate speed 21. Speed is how fast an object moves

30. 4.2Speed 22. MKS units of speed meters/second = m/sec . v = d t

31. 4.2Speed

32. 4.2Speed Instantaneous Speed 23. Instantaneous speed is the speed at an instant of time 24. Speedometer measures instantaneous speed.

33. 4.2Speed The speedometer gives readings of instantaneous speed in both mi/h and km/h.

34. 4.2Speed Average Speed 25. average speed = total distance total time.

35. 4.2Speed Is average speed the same as instantaneous speed?

36. REARRANGE equation: v = d/t 26. HOW FAR: total distance d = average speed X total time d = v • t

37. 27. Odometer measures how far an object travels.

38. 4.2Speed How can you calculate speed?

39. 4.3Velocity 28. Velocity is speed in a specific direction.

40. 4.3Velocity 29. MKS units of Velocity : m/sec

41. 4.3Velocity 30. Velocity is the rate of change of position V = Dx Dt

42. 4.3Velocity 31. Rate always means wrttime

43. 4.3Velocity 32. Speed is a scalar; and Velocity is a vector.

44. 4.3Velocity Constant Velocity 33. Constant velocity means traveling in a straight line at constant speed.

45. 4.3Velocity Changing Velocity 34. Velocity changes if speed changes or direction changes or both change .

46. 4.3Velocity The car on the circular track may have a constant speed but not a constant velocity, because its direction of motion is changing every instant.

47. 4.3Velocity How is velocity different from speed?

48. 35. Acceleration = change in velocitytime intervala = DVDT

49. 36. Acceleration is the rate of change of velocity.

50. 4.4Acceleration 37. Acceleration means decreases or increases in velocity. 38. Decreased acceleration is called deceleration.