Mechanical Advantage – continued

Key lever-related formulas are provided in the above illustration. Take a close look at the top three lever formulas. These formulas provide a relationship between four quantities: F1, L1, F2, and L2. If three of these quantities are known, we can easily calculate the fourth one.

Let’s take a simple example. We are given the following information:

L1 = 10 ft
L2 = 1 ft
F2 = 500 lb

Find the force necessary to lift F2. In other words, we are asked to calculate F1.

Solution

Using the formula for F1 given above, we can calculate F1:

F1 = (1/10) x 500 = 50 lb.

Therefore to lift a weight of 500 lb we only need to apply a force of 50 lb.

What is the value of Mechanical Advantage (MA) in the above example:

MA = 10/1 = 10

In simple language, the mechanical advantage tells us that the lever used in this example will multiply the force by 10.