Mechanical Advantage

To make a lever useful to us, we make L1 greater than L2, as shown in the above illustration. Please pay close attention to the discussion provided here, and make notes for yourself. This is a complex subject but the discussion provided here uses simple terminology. The same principles apply to pulleys as well.

How A Lever Multiplies Force

In the illustration shown here, since L1 is greater than L2, F1 can be much smaller than F2. For example, if F2 represented a weight force equal to 100 lb, we would be able to lift it by applying a much smaller F1 force, say 25 lb. Let’s clarify it further. Let’s say the maximum weight I can manually lift up is 50 lb. It is not possible for me to lift a heavier weight, say 100 lb. If I were to use a lever, I could easily lift a weight of 100 lb or even something heavier.

The magic lies in the fact that L1 is greater than L2. This allows me to use a force of 25 lb as F1 and lift F2 which may be 100 lb or heavier.