Monday, September 9, 2013

Physics - Intro to Pulleys

This will be an overview of pulleys and the assumptions that we make of them in mechanics. Usually when doing these problems we can
  • Ignore friction forces of the rope on the pulley itself
  • Ignore the mass of the pulley or rope
Although these assumptions aren't necessarily true we can assume so if the weights are much larger in comparison to the weight of the pulley, or if there are multiple weights in the same system, that the difference between them is very large.

What is the simplest way that we can see the advantages of using a pulley? In the following picture

We can see a pulley attached to a ceiling moving a weight. The force the hand must exert is divided in two because the Tension force on the rope is evenly divided between rope being pulled by the hand and the portion attached to the ceiling reducing the effort of the person pulling the object up.

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