FIRST-CLASS LEVERS


  • A first-class lever has the fulcrum between the input and output forces.
  • The output force is always in the opposite direction to the input force.


Class 1 lever.jpg
Class 1 Lever


The part of the lever between the resistance/load and the fulcrum is called the resistance/load arm:

resistancearm.gif


The part of the lever between the fulcrum and the effort is called the effort arm:

effortarm.gif

  • The closer you move the fulcrum to the load/resistance arm the easier it is to lift the load.



Ideal Mechanical Advantage: the mechanical advantage of a machine that has no friction

IMA= L in/L out

L in: Length of the input arm

L out: Length of the output arm




∴ Therefore the Ideal mechanical advantage of a first-class lever can be equal to 1, smaller than 1 or greater than 1 because you are able to move and adjust the placement of the fulcrum to make the output arm longer than the input arm or the input arm longer than the output arm.





Examples of first-class levers:




scissors 1.jpg
Scissors
Oars.gif
Oars
class 1 example.jpg
Pliers



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