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Levers

Design & Technology: AQA GCSE, topic 1.5.2

Levers

Levers make lifting or moving something easier. They use mechanical advantage (MA) to do this.

Levers

Levers

  • Mechanical advantage is where the force that comes out is more than the force that is put in.
    • MA = Load/Effort
  • By using levers the force of effort can be reduced for the same load.
  • There are two parts to a lever:
    • A bar.
    • A fulcrum (pivot).
Effort, load and pivot

Effort, load and pivot

  • There are three factors to consider:
    • The effort: the force that is input.
    • The load: the force that is output.
    • Position of the fulcrum (pivot).

Classes of Lever

Levers use mechanical advantage (MA) to make lifting or moving things easier. There are three factors to consider: the effort (the force that is input), the load (the force that is output) and the position of the fulcrum (pivot).

Class 1 - First order lever

Class 1 - First order lever

  • The effort and the load are on either side and the fulcrum is in between.
    • Examples include a pair of scissor and a see-saw.
  • Mechanical advantage (MA) will increase if:
    • The load is closer to the fulcrum.
    • The effort is further away from the fulcrum.
  • The see-saw will have a greater MA if one side is longer than the other.
Class 1 - First order lever

Class 1 - First order lever

Class 1 - First order lever

Class 1 - First order lever

Class 2 - Second order lever

Class 2 - Second order lever

  • The effort is at the opposite end to the fulcrum and the load is in between.
    • Examples include a wheelbarrow and nut cracker.
  • Mechanical advantage (MA) will increase if:
    • The load is closer to the fulcrum.
    • The effort is further away from the fulcrum.
  • The wheelbarrow will have a greater MA if the handle is longer and the load is close to the wheel.
Class 2 - Second order lever

Class 2 - Second order lever

Class 3 - Third order lever

Class 3 - Third order lever

  • The load is at the opposite end to the fulcrum and the effort is in the middle.
    • Examples include tweezers and a stapler.
  • Third order levers are used when you want the force coming out to be less than the force going in.
  • This is very useful for products such as tweezers when a gentle force is needed.
Class 3 - Third order lever

Class 3 - Third order lever

Test yourself on Levers

  • What does MA stand for?

  • What class of lever is this an example of?

  • What class of lever is this an example of?

  • What class of lever is this an example of?

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