Law of the Lever The figure shows a lever system, similar to a seesaw that you might find in a children’s playground. For the system to balance, the product of the weight and its distance from the fulcrum must be the same on each side: that is,
This equation is called the law of the lever and was first discovered by Archimedes (see page 787).
A woman and her son are playing on a seesaw. The boy is at one end, 8 ft from the fulcrum. If the son weighs 100 lb and the mother weighs 125 lb. where should the woman sit so that the seesaw is balanced?
To find: The distance of woman from fulcrum.
Answer to Problem 75E
The distance of woman from fulcrum is 6.4 ft.
Explanation of Solution
Given:
A boy is at one end 8 ft from the fulcrum and the weight of boy is 100 lb.
The weight of woman is 125 lb.
Formula used: Law of the lever
The product of the weight and its distance from the fulcrum must be same on each side,
Calculation:
Let the distance of woman from the fulcrum be x.
Tabulate the given information into the language of algebra.
In words | In algebra |
Distance of woman | x |
Product of weight and distance | 125x |
Model the equation for the above information.
Simplify the above equation for x.
Thus, the distance of woman from fulcrum is 6.4 ft.
Chapter 1 Solutions
Precalculus - A Custom Text for UNLV
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