5.4 Moments, Levers and Gears

• Moment


  Alternative name for the turning effect of a force
• Moment of force


  Equation: Moment = Force x Distance

  Units: Moment (Nm), Force (N), Distance (m)
• Distance measurement used when calculating a moment

  The perpendicular distance from the pivot to the line of action of the force
• If an object is in equilibrium, the clockwise moments are equal to the anticlockwise moments
• Parts of a lever system

  • Load
  • Effort
  • Pivot
• How a lever can be used as a force multiplier

  • If the distance between the effort and pivot is greater than the distance between the pivot and load, the force applied on the load is greater than the effort force. This is since the moment on both the effort and load must be the same.
• Example of when a lever may be used to multiply a force

  • A wrench, which has a long handle so that the force applied by the user is multiplied
• What determines the moment of a gear wheel

  The size of the wheel
• Moment and speed of a larger gear being driven by a smaller gear

  • The larger wheel will rotate more slowly but will also produce a larger moment