moments

• Moment


  The turning force around a fixed pivot
• Things connected by moments

  • Spanner loosening a fixed nut
  • Child on a seesaw
  • Door opening around a fixed hinge
• Moments


  • One moment acting results in a turning force
  • If something is balanced or in equilibrium, the moments are equal and opposite
• Balancing a seesaw


  1. Lighter child sits further away from the pivot

  2. Heavier child sits closer to the pivot
• Size of a moment


  Determined by the force and the distance
• Unit of moment


  Newton-meters (N·m)
• The distance must be the perpendicular distance from the pivot to the force
• Calculating moments


  • Woman tightening a wheel nut (3 N·m)
  • Seesaw with clockwise and anti-clockwise moments
• For something to be balanced, the clockwise and anti-clockwise moments must be equal