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- 1. Dynamics
- 2. Dynamics is the study of things that move, and why they move. fire extinguisher momentum.mpeg
- 4. honda ad
- 5. Basic equation
- 8. <ul><li>The motorcycle was traveling at 250 km/h. </li></ul><ul><li>Convert this to ms -1 </li></ul><ul><li>“ See- think- react” usually takes 1 second. </li></ul><ul><li>How far does the rider travel? </li></ul>
- 9. <ul><li>the bike rider was found INSIDE the car. </li></ul><ul><li>The Volkswagen actually flipped over from the force of impact and landed 3 m from where the collision took place. </li></ul>
- 10. Acceleration equation
- 11. Kinematic Equations
- 13. Displacement/time Graphs stationary d t
- 14. Moving forward constant velocity d t
- 15. <ul><li>Displacement Time Graph </li></ul>d constant Velocity (R) constant Velocity (L) STOP constant Velocity (L) constant Velocity (R) STOP t stopped
- 16. For a displacement/time graph <ul><li>Positive slope means moving to the </li></ul>Negative slope means moving to the right left
- 17. Gradient = Rise Run = Δ d = velocity Δ t Δ d Δ t d t
- 18. d t d d t t Constant gradient Constant velocity Increasing gradient acceleration Decreasing gradient decceleration
- 19. acceleration d t
- 20. decceleration d t
- 21. <ul><li>Velocity/Time Graphs </li></ul>V t Increasing V constant V decreasing V Increasing V decreasing V
- 22. Positive velocity : Moving to the right accelerating deccelerating constant velocity Negative velocity : Moving to the left deccelerating accelerating v t
- 23. Positive area, moving to the right Negative area, moving to the left
- 24. Gradient = Rise Run = Δ v = acceleration Δ t Δ v Δ t v t
- 25. Scalars and Vectors Scalars have only size Distance Speed Vectors have size and direction Displacement m Velocity ms -1 Acceleration ms -2 Force N
- 26. Vectors <ul><li>Adding Vectors. </li></ul><ul><li>When is 3 + 3 not equal to 6? </li></ul><ul><li>Courtney rides 3 km north then 3 km south . </li></ul><ul><li>What is her displacement? </li></ul><ul><li>In this case 3 + 3 = 0 if you take into account direction. </li></ul>
- 27. <ul><li>Sarah rides 3 km north then 3 km east. </li></ul><ul><li>What is her displacement? </li></ul>Displacement is Direction is 045 0
- 28. <ul><li>So you can see that to ADD vectors, you put them tail to head. </li></ul><ul><li>The total is from tail to head </li></ul>A B To find A + B A + B
- 29. <ul><li>The order doesn’t matter </li></ul>A B To find A + B A + B
- 30. Adding Forces <ul><li>What size is the total (net) force? </li></ul>300 N 300 N
- 31. <ul><li>What size is the total (net) force? </li></ul>600 N 300 N
- 32. Find the Net Force 90 0 300 000N 300 000N
- 33. 90 0 TAIL to HEAD TAIL to HEAD
- 34. Adding Velocities <ul><li>Jess is walking at 3.0 ms -1 in the bus. </li></ul><ul><li>The bus is moving at 4.0 ms -1 </li></ul><ul><li>What is her velocity if….. </li></ul>
- 35. Adding Velocities <ul><li>Jess is walking at 3.0 ms -1 in the bus. </li></ul><ul><li>The bus is moving at 4.0 ms -1 </li></ul><ul><li>What is her velocity if….. </li></ul>
- 36. Adding Velocities <ul><li>Jess is walking at 3.0 ms -1 in the bus. </li></ul><ul><li>The bus is moving at 4.0 ms -1 </li></ul><ul><li>What is her velocity if….. </li></ul>
- 37. <ul><li>A plane is pointing north with an airspeed of 400 kmh -1 . </li></ul><ul><li>The wind is from the west at 300 kmh -1 . </li></ul><ul><li>What is the plane’s ground velocity? </li></ul>
- 38. Plane in still air Plane pushed by wind.
- 39. Plane/air Wind/ground plane/ground Speed = θ
- 40. River and Boat
- 41. What direction must the plane point so it flies north ?
- 42. Plane/air Wind/ground plane/ground
- 43. Plane/air Wind/ground plane/ground φ What is the speed? What direction does the pilot point?
- 44. Change in Velocity <ul><li>The change in anything is what it is minus what it was . </li></ul><ul><li>Confused???????? </li></ul><ul><li>What is the change in your height in the last 5 years? </li></ul><ul><li>Height change= height now – height then </li></ul>
- 45. <ul><li>You had $5 yesterday now you have $10 </li></ul><ul><li>What is the change in your wealth? </li></ul><ul><li>You had $10 yesterday now you have $5 </li></ul><ul><li>What is the change? </li></ul><ul><li>You had $5 yesterday now you owe $10 </li></ul><ul><li>What is the change? </li></ul>
- 46. V i = 5 ms -1 What is the ball’s change in velocity? V f = 0 ms -1
- 47. 5 ms -1 3 ms -1 What is the ball’s change in velocity?
- 48. v i v f -v i v f Δ v
- 49. Velocity change What direction is the force of the floor on the ball? Velocity change and force are in the same direction force
- 50. <ul><li>What is the velocity change if the ball hits on an angle? </li></ul>-v i v f Δ v -v i v f v i v f
- 51. Components <ul><li>We have seen that you add vectors tail to head . </li></ul>
- 52. <ul><li>You can also separate a vector into two parts at right angles. </li></ul><ul><li>The parts are called components . </li></ul>OR
- 53. The force from the rope can be split into two components The horizontal component pulls her forward The vertical component tries to lift her.
- 54. Force <ul><li>A force is a </li></ul><ul><li>Newton’s First Law. </li></ul><ul><li>If F net = 0, </li></ul><ul><li>If F net = 0 </li></ul>push or a pull object is at rest or constant velocity object accelerates
- 55. A Force Can Make Things Accelerate
- 57. Adding Forces Thrust force Drag force What is the nett force? Nett force The car accelerates to the right
- 58. Adding Forces Thrust force Drag force What is the nett force? Nett force The car slows down
- 59. If Fnet is in the same direction as the motion, car accelerates velocity F net If Fnet is in the opposite direction to the motion, car deccelerates velocity F net
- 60. Newton’s First Law <ul><li>“ Things like to keep doing what they are doing” </li></ul><ul><li>Or </li></ul><ul><li>“ an object moves at constant velocity unless an unbalanced force acts on it” </li></ul>
- 64. <ul><li>F net = m x a </li></ul>a N kg ms -2 Bigger force. Bigger acceleration Bigger mass. Smaller acceleration v t
- 65. Which accelerates most? F F F F Which accelerates most?
- 66. If an object is dropped, (no air resistance) it accelerates downwards gaining 10 ms -1 every second F g = m x a Weight Force (N) mass (kg) acceleration (10 ms -2 ) g = 10 ms -2
- 67. As an object falls, the air resistance increases F g F g F up F g F up F net = 0 (a = o) Constant velocity (terminal velocity) F g > F up so F net is down Still accelerates, but acceleration gets smaller
- 68. Newton’s Third Law <ul><li>For every action force , </li></ul><ul><li>There is an equal and opposite reaction force </li></ul><ul><li> Acting on a different body </li></ul>Action force (on face) Reaction force (on ball)
- 69. Or….you can’t touch without being touched… Force of Annie on Betty Force of Betty on Annie
- 70. Action force (on wall) Reaction force (on wolfie)
- 73. Action force Reaction force
- 75. ACTION REACTION
- 77. Balloon Rocket Action force (balloon on air) Reaction force (air on balloon)
- 78. Rocket man & summary -
- 80. Momentum
- 81. Momentum is a vector quantity
- 83. Impulse <ul><li>Describe how you catch an egg to minimise the chance of it breaking. </li></ul><ul><li>The damage to the egg (force on it) doesn’t just depend on how fast it’s travelling, but also how fast it stops . </li></ul>
- 84. This is called IMPULSE
- 85. If you jump out a window and hit the ground, your momentum changes. If you hit concrete, your momentum changes quickly ( Δ t is small, F is large) If you hit a trampoline, your momentum changes slowly ( Δ t is large, F is small)
- 86. If you drive a car into a wall, its momentum changes. If the car is rigid, its momentum changes quickly ( Δ t is small, Force is large) If the car crumples, its momentum changes slowly ( Δ t is large, Force is small)
- 87. <ul><li>Road Safety Message </li></ul><ul><li>The Faster you Go the Bigger the Mess! </li></ul>The Faster you Stop the Bigger the Mess!
- 88. <ul><li>Would you rather fall 4 m onto concrete, or 8m into water? Explain. </li></ul>

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