Multiple Pulleys

Here we are using two pulleys, giving us a big advantage. Notice that in this arrangement the weight is attached to the lower pulley block. This pulley block is pulled up by two ropes. Remember we talked about earlier on: The tension in the rope has two properties:

a. It is exactly the same throughout the rope’s length

b. The magnitude of the tension is equal to the applied force.

Therefore, in this case we see that when we apply F1, it does the following:

a. It creates tension in the rope which is equal to F1.

b. The tension acts upward, and since two ropes are actually pulling the weight up, therefore the force used to lift the weight is 2 times F1. The pulley doubles the force which is actually applied to the weight. Therefore, the mechanical advantage in this case is 2.