By Julianne and Ivonne
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