Dynamics
Dynamics is the study of things that move, and why they move. fire extinguisher  momentum.mpeg
 
honda  ad
Basic equation
 
 
<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- ...
<ul><li>the bike rider was found INSIDE the car.  </li></ul><ul><li>The Volkswagen actually flipped over from the force of...
Acceleration equation
Kinematic Equations
 
Displacement/time Graphs stationary d t
Moving forward constant velocity d t
<ul><li>Displacement Time Graph </li></ul>d constant Velocity (R) constant Velocity (L) STOP constant Velocity (L) constan...
For a displacement/time graph <ul><li>Positive  slope means moving to the </li></ul>Negative  slope means moving to the ri...
Gradient =  Rise Run =  Δ  d   = velocity Δ  t Δ  d Δ  t d t
d t d d t t Constant gradient Constant velocity Increasing gradient acceleration Decreasing gradient decceleration
acceleration d t
decceleration d t
<ul><li>Velocity/Time Graphs </li></ul>V t Increasing V constant V decreasing V Increasing V decreasing V
Positive velocity :  Moving to the  right accelerating deccelerating constant velocity Negative velocity :  Moving to the ...
Positive area, moving to the  right Negative area, moving to the  left
Gradient =  Rise Run =  Δ  v   = acceleration Δ  t Δ  v Δ  t v t
Scalars and Vectors Scalars have only  size Distance  Speed Vectors have  size  and  direction Displacement m Velocity ms ...
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 nor...
<ul><li>Sarah rides  3 km north  then  3 km east.   </li></ul><ul><li>What is her displacement? </li></ul>Displacement is ...
<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  h...
<ul><li>The order doesn’t matter </li></ul>A B To find A + B A + B
Adding Forces <ul><li>What size is the total (net) force? </li></ul>300 N 300 N
<ul><li>What size is the total (net) force? </li></ul>600 N 300 N
Find the Net Force 90 0 300 000N 300 000N
90 0 TAIL to HEAD TAIL to HEAD
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>...
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>...
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><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 ...
Plane in still air Plane pushed by wind.
Plane/air Wind/ground plane/ground Speed =  θ
River and Boat
What direction must the plane point so it flies  north ?
Plane/air Wind/ground plane/ground
Plane/air Wind/ground plane/ground φ What is the speed?  What direction does the pilot point?
Change in Velocity <ul><li>The  change  in anything is  what it is  minus  what it was . </li></ul><ul><li>Confused???????...
<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 h...
V i  = 5 ms -1 What is the ball’s change in velocity? V f  = 0 ms -1
5 ms -1 3 ms -1 What is the ball’s change in velocity?
v i v f -v i v f Δ v
Velocity change What direction is the  force  of the floor on the ball? Velocity change  and  force  are in the same direc...
<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
Components <ul><li>We have seen that you add vectors  tail  to  head . </li></ul>
<ul><li>You can also separate a vector into two parts at right angles. </li></ul><ul><li>The parts are called  components ...
The force from the rope can be split into two components The  horizontal  component pulls her forward The  vertical  compo...
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 ...
A Force Can Make Things Accelerate
 
Adding Forces Thrust force Drag force What is the nett force? Nett force The car accelerates to the right
Adding Forces Thrust force Drag force What is the nett force? Nett force The car slows down
If Fnet is in the  same  direction as the motion, car  accelerates velocity F net If Fnet is in the  opposite  direction t...
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 ob...
 
 
 
<ul><li>F net =  m  x  a </li></ul>a N kg ms -2 Bigger force.  Bigger acceleration Bigger mass.  Smaller acceleration v t
Which accelerates most? F F F F Which accelerates most?
If an object is dropped, (no air resistance) it  accelerates downwards gaining 10 ms -1  every  second F g  =  m  x  a Wei...
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 vel...
Newton’s Third Law <ul><li>For every  action force , </li></ul><ul><li>There is an equal and opposite  reaction force </li...
Or….you can’t touch without being touched… Force of Annie on Betty Force of Betty on Annie
Action force (on wall) Reaction force (on wolfie)
 
 
Action force Reaction force
 
ACTION REACTION
 
Balloon Rocket Action force (balloon on air) Reaction force (air on balloon)
Rocket man & summary -
 
Momentum
Momentum is a vector quantity
 
Impulse <ul><li>Describe how you catch an egg to minimise the chance of it breaking. </li></ul><ul><li>The damage to the e...
This is called IMPULSE
If you jump out a window and hit the ground, your momentum changes. If you hit concrete, your  momentum changes  quickly  ...
If you drive a car into a wall, its momentum changes. If the car is rigid, its  momentum changes  quickly  ( Δ t is small,...
<ul><li>Road Safety Message </li></ul><ul><li>The Faster you Go the Bigger the Mess! </li></ul>The Faster you  Stop  the B...
<ul><li>Would you rather fall 4 m onto concrete, or 8m into water? Explain. </li></ul>
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Dynamics (motion)

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Dynamics (motion)

  1. 1. Dynamics
  2. 2. Dynamics is the study of things that move, and why they move. fire extinguisher momentum.mpeg
  3. 4. honda ad
  4. 5. Basic equation
  5. 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>
  6. 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>
  7. 10. Acceleration equation
  8. 11. Kinematic Equations
  9. 13. Displacement/time Graphs stationary d t
  10. 14. Moving forward constant velocity d t
  11. 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
  12. 16. For a displacement/time graph <ul><li>Positive slope means moving to the </li></ul>Negative slope means moving to the right left
  13. 17. Gradient = Rise Run = Δ d = velocity Δ t Δ d Δ t d t
  14. 18. d t d d t t Constant gradient Constant velocity Increasing gradient acceleration Decreasing gradient decceleration
  15. 19. acceleration d t
  16. 20. decceleration d t
  17. 21. <ul><li>Velocity/Time Graphs </li></ul>V t Increasing V constant V decreasing V Increasing V decreasing V
  18. 22. Positive velocity : Moving to the right accelerating deccelerating constant velocity Negative velocity : Moving to the left deccelerating accelerating v t
  19. 23. Positive area, moving to the right Negative area, moving to the left
  20. 24. Gradient = Rise Run = Δ v = acceleration Δ t Δ v Δ t v t
  21. 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
  22. 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>
  23. 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
  24. 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
  25. 29. <ul><li>The order doesn’t matter </li></ul>A B To find A + B A + B
  26. 30. Adding Forces <ul><li>What size is the total (net) force? </li></ul>300 N 300 N
  27. 31. <ul><li>What size is the total (net) force? </li></ul>600 N 300 N
  28. 32. Find the Net Force 90 0 300 000N 300 000N
  29. 33. 90 0 TAIL to HEAD TAIL to HEAD
  30. 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>
  31. 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>
  32. 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>
  33. 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>
  34. 38. Plane in still air Plane pushed by wind.
  35. 39. Plane/air Wind/ground plane/ground Speed = θ
  36. 40. River and Boat
  37. 41. What direction must the plane point so it flies north ?
  38. 42. Plane/air Wind/ground plane/ground
  39. 43. Plane/air Wind/ground plane/ground φ What is the speed? What direction does the pilot point?
  40. 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>
  41. 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>
  42. 46. V i = 5 ms -1 What is the ball’s change in velocity? V f = 0 ms -1
  43. 47. 5 ms -1 3 ms -1 What is the ball’s change in velocity?
  44. 48. v i v f -v i v f Δ v
  45. 49. Velocity change What direction is the force of the floor on the ball? Velocity change and force are in the same direction force
  46. 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
  47. 51. Components <ul><li>We have seen that you add vectors tail to head . </li></ul>
  48. 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
  49. 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.
  50. 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
  51. 55. A Force Can Make Things Accelerate
  52. 57. Adding Forces Thrust force Drag force What is the nett force? Nett force The car accelerates to the right
  53. 58. Adding Forces Thrust force Drag force What is the nett force? Nett force The car slows down
  54. 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
  55. 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>
  56. 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
  57. 65. Which accelerates most? F F F F Which accelerates most?
  58. 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
  59. 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
  60. 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)
  61. 69. Or….you can’t touch without being touched… Force of Annie on Betty Force of Betty on Annie
  62. 70. Action force (on wall) Reaction force (on wolfie)
  63. 73. Action force Reaction force
  64. 75. ACTION REACTION
  65. 77. Balloon Rocket Action force (balloon on air) Reaction force (air on balloon)
  66. 78. Rocket man & summary -
  67. 80. Momentum
  68. 81. Momentum is a vector quantity
  69. 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>
  70. 84. This is called IMPULSE
  71. 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)
  72. 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)
  73. 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!
  74. 88. <ul><li>Would you rather fall 4 m onto concrete, or 8m into water? Explain. </li></ul>

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