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Technology: Engineering Our World
In other words, the human effort applied is being multiplied by the
machine. In this case, the machine is a lever. The effort required becomes
less as the fulcrum and resistance are brought closer together. However,
as the fulcrum and resistance are moved closer, the load moves a shorter
distance. See Figure 8-12.
Fulcrum (F)
Effort (E)
Resistance (R)
gure 8-10. In a Class 3 lever,
the effort is between the resistance
and fulcrum.
Arm
Spade
Fishing rod
Canoe paddle
Tweezers
Bat
gure 8-11. Everyday uses of Class 3 levers.
A
B
More effort
Less effort
Resistance
Movement
Movement
Resistance
gure 8-12. Moving the fulcrum
of a Class 1 lever affects both the
effort required and the distance the
object is moved.