See figure 5-3 for an illustration of the three classes of levers.
a. First Class. In a first class lever, the weight to be moved is
at one end of the lever, the applied force is at the other end, and the fulcrum (the pivot
or turning point) is between the two.
b. Second Class. In a second class lever, the weight to be moved is
between the applied force and the fulcrum. This type of lever enables a weight to be moved
with less force than would be required without a lever. (Many feel that there are no
second class levers in the human body.)
c. Third Class. In a third class lever, the weight to be moved is
at one end of the lever, the fulcrum is at the other end, and the applied force is between
the weight and the fulcrum. This type of lever provides speed, but a greater amount of
force is required for a given weight. This is the most common type of lever in the human
body.
