Finding the Right Weight for the Lever
21) If 50 pounds were placed on a lever, 3 feet to the left
of the fulcrum, how much weight would have to be placed at 5 feet
to the right of the fulcrum to have an even balance?
Using the lever formula makes figuring problems of this nature
very simple.
When we think of a lever, we might think of a teeter-totter on
which if weight were placed just right, by scooting up or scooting
back, there could be an even balance -- regardless of how different
the two people were in weight..
Here's the formula:
weight * distance = distance * weight
e.g. 100 * 6 = 10 * 60 This means that on our lever we
have 100 pounds that is 6 feet from the fulcrum; and, on the other
side, there is 60 pounds that is 10 feet from the fulcrum, for
an even balance. The equation is true (600 = 600).
With that in mind, let us answer the above question:
50 * 3 = 5 * x
150 = 5x
30 = x
Therefore, to make the lever balance with 50 pounds on one
side (3 feet from the fulcrum), we would have to place 30 pounds 5
feet from the fulcrum on the other side.