360
96
¼
961 x
961
3 : 75 ¼x
Hence she must sit 3.75 feet from the fulcrum.
EVALUATION: Check the equation:
WL¼wl
120 ð 3 Þ¼ 96 ð 3 : 75 Þ
360 ¼ 360
The fulcrum of a lever does not have to be at its center.
EXAMPLE:The fulcrum of a lever is 3 feet from the end of a 10-foot lever.
On the short end rests an 84-pound weight. How much weight must be placed
on the other end to balance the lever?
SOLUTION:
GOAL: You are being asked to find how much weight is needed to balance
the lever.
STRATEGY: Letx¼the weight of the object needed.
WL¼wl
84 ð 3 Þ¼xð 7 Þ
See Figure 16-3.
Fig. 16-3.
174 LESSON 16 Solving Lever Problems