P4 - Explaining Motion

Speed
1. Speed (m/s) = Distance Traveled (m) / Time Taken (s)
2. Distance (m) = Speed (m/s) X Time Taken (s)
3. Time (s) = Distance (m) / Speed (m/s)
Distance-Time Graphs
1. Gradient = Speed
2. Flat sections are where it's stationary
3. The steeper the gradient, the faster it is going
4. Straight lines meaning the object is moving at a constant speed
5. A steeping curve = Acceleration
6. A leveling off curve = Deceleration
7. Speed = Gradient = Vertical / Horizontal
Displacement-Time Graphs
1. Displacement can be Positive or Negative
2. They show is two different objects travelling different directions from a point
Acceleration
1. Acceleration (m/s~2) = Change in Velocity (m/s) / Time Taken (s)
2. Change in Velocity (m/s) = Acceleration (m/s~2) X Time Taken (s)
3. Time Taken (s) = Change in Velocity (m/s) / Acceleration (m/s~2)
Velocity-Time Graphs
1. Gradient = Acceleration
2. Flat sections = Constant Speed
3. The steeper the gradient, the greater the acceleration or deceleration
4. Uphill sections are acceleration
5. Downhill sections are deceleration
6. Negative Velocity means the object is travelling in the opposite direction
Forces and Friction
1. Forces occur when two object interact
2. An object resting on a surface experiences a reaction force
3. Moving objects normally experience friction
4. Three types of Friction
  1. Friction between solid surfaces which are gripping
  2. Friction between solid surfaces which are sliding past each other
    1. Can be reduced by adding a lubricant
  3. Resistance or "Drag" from fluids
Acceleration
1. When a car exerts a bigger driving force than the drag counter force, the car will then accelerate.
2. The bigger the force, the greater the acceleration
Momentum
1. Momentum (kg m/s) = Mass (kg) X Velocity (m/s)
2. Velocity (m/s) = Momentum (kg m/s) / Mass (kg)
3. Mass (kg) = Momentum (kg m/s) / Velocity (m/s)
Change of Momentum
1. Change of Momentum (kg m/s) = Resultant Force (N) x Time for which the force acts (s)
2. Resultant Force (N) = Change of Momentum (kg m/s) / Time for which the force acts (s)
3. Time for which the force acts (s) = Change of Momentum (kg m/s) / Resultant Force (N)
Car Safety Features Reduce Forces
1. Crumple Zones
  1. Increases the time taken for the car to stop
2. Air Bags
  1. Slows the passenger more gradually
3. Seat Belts
  1. Increases the time taken for the wearer to stop (reduces the forces acting on the chest)
4. Helmets
  1. Increases the time taken for your head to come to a stop if it hits something hard
Work
1. When a force moves an object, it does work and energy is transferred to the object
2. Amount of energy transferred (J) = Work Done (J)
Work done by a force
1. Work done by a force (J) = Force (N) x Distance moved in direction of force (m)
2. Force (J) = Work done by a force (J) / Distance moved in direction of force (m)
3. Distance moved in direction of force (m) = Work done by a force (J) / Force (N)
Kinetic Energy
1. Kinetic Energy (J) = 1/2 x Mass (kg) x Velocity~2 ([m/s]~2)
2. Mass (kg) = 1/2 x Kinetic Energy (J) / Velocity~2 ([m/s]~2)
3. Velocity~2 ([m/s]~2) = 1/2 x Kinetic Energy (J) / Mass (kg)
GPE
1. Change in GPE
  1. Change in GPE (J) = Weight (N) x Vertical Height Difference (m)
  2. Weight (N) = Change in GPE (J) / Vertical Height Difference (m)
  3. Vertical Height Difference (m) = Change in GPE (J) / Weight (N)
2. Kinetic Energy Gained - GPE Lost

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P4 - Explaining Motion

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	Created by Matthew Jones about 11 years ago