levers and gears

• Lever


  A device that transmits the turning effects of forces
• Levers


  • Hammer used to remove a nail
  • Crowbar used to lift a plank of wood
• Levers


  • Force multipliers
• How a lever works

  1. Apply a force of 10 Newtons on the right side

  2. Distance from force to pivot is 1 meter

  3. Lifting force of 50 Newtons on the left side

  4. Distance from left force to pivot is 0.2 meters

  5. Lever multiplies the force by 5 times
• Moment on the right side

  10 Newton meters
• Moment on the left side

  10 Newton meters
• Gears can also transmit the effect of a force
• Gears in machines


  • Cars
• How gears transmit force

  1. Gear A is connected to the engine's turning force

  2. Gear B is connected to the wheels

  3. Gear B has twice the radius of Gear A

  4. Turning effect of Gear B is twice that of Gear A

  5. Turning effect of the engine is doubled as transmitted to the wheels

  6. Gear A rotates twice for every one rotation of Gear B
• You will find plenty of questions on levers and gears in the revision workbook
• Levers and gears can transmit the turning effects of forces
• Moment


  The turning effect of a force, calculated as force (N) x distance (m)
• Levers


  • Hammer removing a nail
  • Crowbar lifting a plank of wood
• Levers


  • Force multipliers
• Using a lever to lift a load

  1. Apply force of 10 N on right side, 1 m from pivot

  2. Lifting force of 50 N on left side, 0.2 m from pivot

  3. Lever multiplies force by 5 times
• Moment on right side

  10 N x 1 m = 10 N.m
• Moment on left side

  50 N x 0.2 m = 10 N.m
• Gears


  Transmit turning force from one gear to another
• Gears in machines


  • Car - gear A connected to engine, gear B connected to wheels
• Gear B has twice the radius of gear A


  Turning effect of gear B is twice that of gear A
• Gear A rotates twice for every 1 rotation of gear B


  Work done by the two gears is the same