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Technology: Engineering Our World
In Class 3 levers, the effort is applied between the resistance and the
fulcrum, as shown in Figure 8-10. Some applications of Class 3 levers are
illustrated in Figure 8-11.
From the many examples shown, you can see that some levers are
designed to increase the force available. Examples are a wheelbarrow, a
bar used to move a crate, and a garden spade. Other levers are designed
to increase the distance a force moves or the speed at which it moves.
Examples are a fishing rod and a human arm.
Fulcrum (F)
Effort (E) Resistance (R)
gure 8-6. In a Class 1 lever,
the fulcrum is between the effort
and resistance.
Rowing with oars
Claw hammer
Lifting a crate
Seesaw
Scales
Scissors
gure 8-7. Everyday uses of Class 1 levers.