Dynamics (motion)
- 1.
- 2. Dynamics is thestudy of things that move, and why they move. fire extinguisher momentum.mpeg
- 3.
- 4.
- 5.
- 6.
- 7.
- 8. The motorcycle wastraveling at 250 km/h. Convert this to ms -1 “ See- think- react” usually takes 1 second. How far does the rider travel?
- 9. the bike riderwas found INSIDE the car. The Volkswagen actually flipped over from the force of impact and landed 3 m from where the collision took place.
- 10.
- 11.
- 12.
- 13.
- 14. Moving forward constantvelocity d t
- 15. Displacement Time Graphd constant Velocity (R) constant Velocity (L) STOP constant Velocity (L) constant Velocity (R) STOP t stopped
- 16. For a displacement/timegraph Positive slope means moving to the 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 dd t t Constant gradient Constant velocity Increasing gradient acceleration Decreasing gradient decceleration
- 19.
- 20.
- 21. Velocity/Time Graphs Vt 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, movingto 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 VectorsScalars 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 3 + 3 = 0 if you take into account direction.
- 27. Sarah rides 3 km north then 3 km east. What is her displacement? Displacement is Direction is 045 0
- 28. So you cansee that to ADD vectors, you put them tail to head. The total is from tail to head A B To find A + B A + B
- 29. The order doesn’tmatter A B To find A + B A + B
- 30. Adding Forces Whatsize is the total (net) force? 300 N 300 N
- 31. What size isthe total (net) force? 600 N 300 N
- 32. Find the NetForce 90 0 300 000N 300 000N
- 33. 90 0 TAILto HEAD TAIL to HEAD
- 34. Adding Velocities Jessis walking at 3.0 ms -1 in the bus. The bus is moving at 4.0 ms -1 What is her velocity if…..
- 35. Adding Velocities Jessis walking at 3.0 ms -1 in the bus. The bus is moving at 4.0 ms -1 What is her velocity if…..
- 36. Adding Velocities Jessis walking at 3.0 ms -1 in the bus. The bus is moving at 4.0 ms -1 What is her velocity if…..
- 37. A plane ispointing 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?
- 38. Plane in stillair Plane pushed by wind.
- 39. Plane/air Wind/ground plane/groundSpeed = θ
- 40.
- 41. What direction mustthe plane point so it flies north ?
- 42.
- 43. Plane/air Wind/ground plane/groundφ What is the speed? What direction does the pilot point?
- 44. Change in VelocityThe 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
- 45. You had $5yesterday 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 What is the change?
- 46. V i = 5 ms -1 What is the ball’s change in velocity? V f = 0 ms -1
- 47. 5 ms -13 ms -1 What is the ball’s change in velocity?
- 48. v i vf -v i v f Δ v
- 49. Velocity change Whatdirection is the force of the floor on the ball? Velocity change and force are in the same direction force
- 50. What is thevelocity change if the ball hits on an angle? -v i v f Δ v -v i v f v i v f
- 51. Components We haveseen that you add vectors tail to head .
- 52. You can alsoseparate a vector into two parts at right angles. The parts are called components . OR
- 53. The force fromthe rope can be split into two components The horizontal component pulls her forward The vertical component tries to lift her.
- 54. Force A forceis a Newton’s First Law. If F net = 0, If F net = 0 push or a pull object is at rest or constant velocity object accelerates
- 55. A Force CanMake Things Accelerate
- 56.
- 57. Adding Forces Thrustforce Drag force What is the nett force? Nett force The car accelerates to the right
- 58. Adding Forces Thrustforce Drag force What is the nett force? Nett force The car slows down
- 59. If Fnet isin 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“ Things like to keep doing what they are doing” Or “ an object moves at constant velocity unless an unbalanced force acts on it”
- 61.
- 62.
- 63.
- 64. F net = m x a 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 objectis 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 objectfalls, 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 LawFor every action force , There is an equal and opposite reaction force Acting on a different body Action force (on face) Reaction force (on ball)
- 69. Or….you can’t touchwithout being touched… Force of Annie on Betty Force of Betty on Annie
- 70. Action force (onwall) Reaction force (on wolfie)
- 71.
- 72.
- 73.
- 74.
- 75.
- 76.
- 77. Balloon Rocket Actionforce (balloon on air) Reaction force (air on balloon)
- 78. Rocket man &summary -
- 79.
- 80.
- 81. Momentum is avector quantity
- 82.
- 83. Impulse Describe howyou catch an egg to minimise the chance of it breaking. The damage to the egg (force on it) doesn’t just depend on how fast it’s travelling, but also how fast it stops .
- 84. This is calledIMPULSE
- 85. If you jumpout 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 drivea 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. Road Safety MessageThe Faster you Go the Bigger the Mess! The Faster you Stop the Bigger the Mess!
- 88. Would you ratherfall 4 m onto concrete, or 8m into water? Explain.