moments

• • a moment is the turning effect of a force
  • moment = force x distance
• spanner example:

  • force on spanner causes moment on nut
  • nut acts as pivot
  • large force or distance creates larger moment
• spanner example:

  • pushing perpendicular to spanner causes maximum moment
  • pushing at smaller angle creates smaller distance, so, smaller moment
• • a lever consists of a pivot, an effort and a load
• • levers increase distance from pivot where force is applied
  • less force needed to get same moment
  • so, levers make it easier to do work
• • the longer the lever, and the further the effort acts from pivot, the greater force on load will be
• • gears are wheels with toothed edges that rotate on axle
  • teeth of gears interlock, so turning one gear causes another to turn in opposite direction
  • transmit rotational effect of force
• • a larger gear will rotate more slowly, but with a greater moment, so distance to pivot is greater
  • a smaller gear will rotate more quickly, but with a smaller moment, so distance to pivot is smaller