1. Forces and Motion

• Resistive Forces : 

  • Friction
  • Air Resistance
• Once it reaches it elastic limit, the spring can no longer go back to its original shape due to the particles having shifted.
• In the first law, an object will not change its motion unless a force acts on it. 
• In the second law, the resultant force on an object is equal to its mass times its acceleration. 
• In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction
• Average Speed


  Total Distance Travelled/Total Time Taken
• Gradient


  Change in y/Change in x
• Acceleration


  Change in velocity/Time Taken
• Units


  • Distance/Displacement: m
  • Time: s
  • Speed/velocity: m/s
  • Acceleration: m/s^2
• Distance


  Has magnitude and direction (How fast it is), doesn't have direction
• Displacement


  Distance with direction (Positive direction is positive, negative direction is negative)
• Speed


  Has magnitude, doesn't have direction
• Velocity


  Speed with magnitude and direction
• Quantities


  • Displacement and Velocity: Vector quantity
  • Distance and Speed: Scalar quantity
• Scalar


  Has only magnitude
• Vector quantity


  Has magnitude and direction
• Distance Time Graph


  1. If y axis/distance stays the same, object is the same distance/stationary

  2. Gradient of graph is speed of object

  3. Flattening curve and straight line = vehicle slowing down and becoming stationary

  4. Steeper curve = speed accelerating
• Gradient of distance time graph


  Speed of object
• Concave curve


  Increasing speed
• Convex curve


  Decreasing speed
• Speed Time Graph


  1. Gradient is acceleration

  2. Area under graph is equal to distance travelled
• Displacement Time Graph


  1. Gradient is equal to velocity

  2. Positive/negative gradient equals direction
• Force


  Push or pull
• Weight


  Mass(Kg) x g(10)
• Weight is not mass, mass is kg, g...
• Resistive Forces


  • Friction
  • Air Resistance
• SI Units


  • Force - Newton
  • Weight - Newton
• Measure object on mass balance


  Find weight of object by converting from mass
• Hooke's Law


  Extension of an elastic object is proportional to the applied force with the proportional limit
• F


  Force (Weight)
• K


  Spring Constant (How stiff the spring is)
• Gradient of force-extension graph


  Spring Constant (Units = N/Length)
• Limit of proportionality


  Extension beyond which Hooke's law no longer applies
• Weight-length of spring graph never goes through (0,0) because it does not take away the original length</b>
• Once elastic limit reached, spring can no longer go back to original shape due to particles having shifted
• F


  Net force
• If no resultant force (Acceleration = 0), motion is either stationary or moving at constant speed
• Acceleration


  Rate of change with speed
• Force


  Proportional to acceleration
• Acceleration


  Inversely proportional to mass