Levers and Gears

• Moments play a part in a lot of mechanical devices, from clocks to wheelbarrows
• Moments


  Can help you get the most out of a small force, and allow you to transmit forces across a distance
• Levers


  • Increase the distance from the pivot at which the force is applied
  • Make it easier to do work, e.g. lift a load or turn a nut
• Simple Levers


  • Long sticks or bars
  • Wheelbarrows
• Gears


  • Circular discs with 'teeth' around their edges
  • Their teeth interlock so that turning one causes another to turn, in the opposite direction
  • Used to transmit the rotational effect of a force from one place to another
  • Different sized gears can be used to change the moment of the force - a force transmitted to a larger gear will cause a bigger moment, as the distance to the pivot is greater
  • The larger gear will turn slower than the smaller gear
• Since MFd


  Less force is needed to get the same moment
• Levers make it easier to do work