P3 - B

  • Created by: zoolouise
  • Created on: 02-06-15 19:01
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  • Changing speed
    • Speed-time graphs
      • A change of speed per unit time is called acceleration.
      • If the speed is increasing, the object is accelerating. If the speed is decreasing, the object is decelerating.
    • Acceleration
      • Acceleration = change in speed (or velocity) / time taken
      • Acceleration is measured in metres per second squared.
      • A negative acceleration shows the car is decelerating.
    • Relative velocities
      • Velocity is a vector, it has both size (speed) and direction
      • When two cars are moving past each other their relative velocity is ;
        • The sum of their individual velocities if they are moving in opposite directions
          • The different of their individual velocities if they are moving in the same direction.
    • Circular motion
      • A vehicle may go around a roundabout at a constant speed but it's accelerating.
        • This is because the direction of travel is changing, it isnt going in a straight line.
      • The driver needs to apply force towards the center of the roundabout to change direction. This gives the vehicle an acceleration directed towards the centre of the roundabout.
      • Any object moving along a circular path moves at a tangent to the circle, or arc of a circle.


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