1. Dynamics

2. Dynamics is the study of things that move, and why they move.

4. Basic equation

7. The motorcycle was traveling at 250 km/h.
Convert this to ms-1
“See- think- react” usually takes 1 second.
How far does the rider travel before braking?

8. the bike rider was found INSIDE the car.
The Volkswagen actually flipped over from the force of impact and landed 3 m from where the collision took place.  

9. Acceleration equation

10. Kinematic Equations

11. A cliff on the Milford Track is called “10 second cliff”
Why?
How high is it?

13. Displacement/time Graphs (not assessed)
stationary

14. d t
Moving forward constant velocity

15. Displacement Time Graph
STOP d
constant
Velocity (L)
stopped
STOP
constant
Velocity (R)
constant
Velocity (L)
constant
Velocity (R)

16. For a displacement/time graph
Positive slope means moving to the
right
Negative slope means moving to the
left

17. d t
Δ d
Δ t
Gradient = Rise
= Δ d = velocity
Δ t
Run

18. Constant gradient Constant velocity Increasing gradient acceleration
Decreasing gradient
decceleration d t

19. d t
acceleration

20. d t
decceleration

21. V t Velocity/time Graphs (not assessed) constant V Increasing V
decreasing V
decreasing V
Increasing V V t

22. Positive velocity : Moving to the right
accelerating
deccelerating
constant velocity v t
Negative velocity : Moving to the left
accelerating
deccelerating

23. Positive area, moving to the right
Negative area, moving to the left

24. v t
Δ v
Δ t
Gradient = Rise
= Δ v = acceleration
Δ t
Run

25. Scalars Vectors Scalars and Vectors have only size
Distance
Speed
Vectors
have size and direction
Displacement m
Velocity ms-1
Acceleration ms-2
Force N

26. Vectors Adding Vectors. When is 3 + 3 not equal to 6?
Courtney rides 3 km north then 3 km south.
What is her displacement?
In this case = 0 if you take into account direction.

27. Displacement is Direction is 0450
Sarah rides 3 km north then 3 km east.
What is her displacement?
Displacement is
Direction is
0450

28. So you can see that to ADD vectors, you put them tail to head.
The total is from tail to head B A
To find A + B
A + B

29. The order doesn’t matterB
A + B A
To find A + B

30. Adding Forces
What size is the total (net) force?
300 N

31. What size is the total (net) force?

32. Find the Net Force N
900 N

33. TAIL to HEAD
900
TAIL to HEAD

34. A Skier on the Slope
why does her acceleration depend on the angle of the slope?

35. consider the forces on her

36. consider the forces on her

37. consider the forces on herθ θ

38. changing the angle

39. Adding Velocities Jess is walking at 3.0 ms-1 in the bus.
The bus is moving at 4.0 ms-1
What is her velocity if…..

40. Adding Velocities Jess is walking at 3.0 ms-1 in the bus.
The bus is moving at 4.0 ms-1
What is her velocity if…..

41. Adding Velocities Jess is walking at 3.0 ms-1 in the bus.
The bus is moving at 4.0 ms-1
What is her velocity if…..

43. River and Boat

44. A plane is pointing north with an airspeed of 400 kmh-1.
The wind is from the west at 300 kmh-1.
What is the plane’s ground velocity?

45. Plane in still air
Plane pushed by wind.

46. Wind/ground
Plane/air
plane/ground
Speed = θ

47. What direction must the plane point so it flies north?
Plane in still air
Plane pushed by wind.

48. Wind/ground
plane/ground
Plane/air

49. φ What is the ground speed? Wind/ground plane/ground
What direction does the pilot point?
Plane/air φ

50. Change in Velocity
The change in anything is what it is minus what it was.
Confused????????
What is the change in your height in the last 5 years?
Height change= height now – height then

51. You had $5 yesterday now you have $10
What is the change in your wealth?
You had $10 yesterday now you have $5
What is the change?
You had $5 yesterday now you owe $10

52. Vi = 5 ms-1
Vf = 0 ms-1
What is the ball’s change in velocity?

53. What is the ball’s change in velocity?
5 ms-1
3 ms-1

54. Δv vi
-vi vf vf

55. What direction is the force of the floor on the ball?
Velocity change and force are in the same direction
Velocity change
force

56. What is the velocity change if the ball hits on an angle?vi vf Δv
-vi
-vi vf vf

57. Components
We have seen that you add vectors tail to head.

58. You can also separate a vector into two parts at right angles.
The parts are called components. OR

59. The force from the rope can be split into two components
The horizontal component pulls her forward
The vertical component tries to lift her.