First Class Lever
What Are First Class Levers?
In a first class lever, the fulcrum is placed between the applied force and the
load.
A balance scale is one common example of the first class lever. In this case, the
fulcrum is located exactly between the force and load. Note that the load in this
example is not a resultant force as it is with most lever applications. Balance
scales can be used to compare the weight of two objects or compare the weight
of one object to a known weight. If the force and load are equal, the lever arm
will balance horizontally.
First Class Lever
Common examples of
first-class levers include
crowbars, seesaws,
scissors, pliers, tin snips
(in pairs)
Second Class Lever
What is a Second Class Lever?
In second class levers, the load is between the force and fulcrum on the lever arm, as
shown in the figure. In this kind of lever, the force is always further from the fulcrum
than the load. As a result, the load does not move as far as the applied force, but the
force of the load will always be greater than the applied force. The closer the load is to
the fulcrum, the more the force of the load increases and the easier it becomes to
raise the load.
The direction of the force and the load always oppose one another in a second class
lever. A second class lever always magnifies force and decreases the distance moved.
Second Class Lever
Example of a Second Class Lever
A wheelbarrow is an example of
a second class lever. The axle of
the wheel is the fulcrum, the
load is that which is being
carried and the force is applied
to the handles.
Third Class Lever
What is a Third Class Lever?
In a third class lever, the force is between the fulcrum and the load on the lever arm.
Since the load is further from the fulcrum than the applied force, the magnitude of
the load is less than that of the applied force.
In a third class lever, the distance the load moves is greater than the distance the
force moves. Therefore a third class lever always magnifies the distance moved and
reduces the magnitude of the load.
Third Class Lever
Examples of thirdclass levers include
fishing rods, an
arm, a hammer,
etc.