Moments

• Moment


  The turning effect of a force around a fixed point, the pivot
• Examples of moments


  • Door opening around a fixed hinge
  • Seesaws
  • Scissors
  • Spanner turning around a nut
• Moment


  • Measured in Newton metres
  • Depends on the size of the force applied and the perpendicular distance from the pivot to the line of action of the force
• Calculating a moment


  Moment = Force x Perpendicular Distance from Pivot
• Lever


  • A rigid body that rotates about a pivot or fulcrum
• Calculating a moment using a lever

  Moment = Force x Perpendicular Distance from Pivot
• Objects can experience more than one moment, which can combine or work against each other</b>
• In a stable or balanced system, the anticlockwise moments are equal to the clockwise moments
• Principle of moments


  For an object to be balanced, the total clockwise moment must equal the total anti-clockwise moment
• Balancing a seesaw


  1. Total anti-clockwise moment = total clockwise moment

  2. Use the equation: Moment = Force x Distance from Pivot
• Spanners


  • Used to turn nuts and bolts
  • Can use a short spanner with a large force or a long spanner with a small force to undo a tight nut
• Levers


  • Can be used to apply a small force to lift a large load, e.g. a screwdriver to open a paint can lid
• Calculating an upwards force using a lever

  1. Anticlockwise moment = Clockwise moment

  2. Use the equation: Moment = Force x Distance from Pivot