Physics

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  • Created by: Ashleigh
  • Created on: 30-11-12 18:31
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  • Physics
    • Resultant Force
      • An object has many different forces adding upon it.
        • These can be added up into a single force: the resultant force.
      • When all the forces are balanced, the resultant force is zero.
        • A stationary object remains stationary.
        • Moving objects keep moving at the same pace and in the same direction.
      • When all the forces are not balanced, the resultant force is not zero
        • In this case the object accelerates in the direction of the resultant force.
        • A stationary object begins to move in the direction of the resultant force.
        • A moving object will speed up, slow down or change direction depending on the resultant force.
      • Force, Mass and Acceleration.
        • Size of force: Obejcts accelerate in the direction of resultant force
          • Bigger the resultant force the bigger the acceleration.
            • Doubling the size of the resultant force doubles the acceleration.
        • Mass: A force on a large mass will accelerate it less than the same force on a smaller mass.
          • Size of force: Obejcts accelerate in the direction of resultant force
            • Bigger the resultant force the bigger the acceleration.
              • Doubling the size of the resultant force doubles the acceleration.
          • Doubling the mass halves the acceleration.
        • Calculating Acceleration: A = F/M
          • F = Resultant Force, Newtons (N)
          • A = Acceleration of the object, Metres per seconds (M/Ssquare)
          • M = Mass, Kilograms (KG)
    • Forces and motion
      • Distance-time graphs
        • Vertical axis = distance
        • Horizontal axis = time
        • When an object is stationary, the line on the graph is horizontal
        • When an object is moving at a steady in a straight line, the line on the graph is also straight but sloped.
          • Steeper the line the greater the speed of the object.
      • Calcuating speed
        • Speed (m/s) = Distance travelled (m) / Time taken (s)
      • Velocity-time graphs
        • The velocity of an object is it's speed in a particular direction
        • Two different cars will have different velocities if they are travelling at:
          • The same speed but in different directions.
          • The different speeds in the same direction
            • different speeds in different directions
          • different speeds in different directions
        • Vertical axis = Velocity of the object
        • Horizontal axis = time
        • when an object is moving with a constant velocity, the line on the graph is horizontal
        • when an object is moving with a constant acceleration, the line is straight but steep
          • The steeper the line, the greater the acceleration.
          • a line sloping downwards - with a negative gradient - represents an object with a constant deceleration (slowing down)
        • Do not confuse
          • Distance-time graphs
            • Vertical axis = distance
            • Horizontal axis = time
            • When an object is stationary, the line on the graph is horizontal
            • When an object is moving at a steady in a straight line, the line on the graph is also straight but sloped.
              • Steeper the line the greater the speed of the object.
      • Acceleration
        • A = (u-v) / T
          • A = Acceleration (m/ssquare)
          • u = final velocity (m/s)
          • v = starting velocity (m/s)
          • T = time taken (s)
  • Moving objects keep moving at the same pace and in the same direction.
  • You can not possiblity tell which is correct unless you know if the object is moving or not.
    • A moving object will speed up, slow down or change direction depending on the resultant force.
    • A stationary object begins to move in the direction of the resultant force.
    • A stationary object remains stationary.
  • To calcuate the gradient of the line divide the change in the vertical axis by the change in the horizontal axis

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