By Julianne and Ivonne


A lever is a simple machine that makes work easier for use; it involves moving a load around a pivot using a force.


  • Seesaw
  • Scissors
  • Crowbar


Lever, simple machine consisting of a rigid bar that rotates about a fixed point, called a fulcrum. Levers affect the effort, or force, needed to do a certain amount of work, and are used to lift heavy objects.

The general formula for the mechanical advantage (MA) of levers:

Or you can use the ratio of the input arm length to the output arm length:

MAlever = Fo (output force)/ Fi (input force)

MAlever = Li (length of input arm) /Lo (length of output arm)


1. A construction worker uses a board and log as a lever to lift a heavy rock. If the input arm is 3 meters long and the output arm is 0.75 meters long, what is the mechanical advantage of the lever?

3 meters /.75 meters = 4

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