What are the advantages and disadvantages of using a pulley?

Answer 1

Advantages - a pulley allows you to apply force in any direction, not just the one in which the force is to applied. Multiple pulleys yield a mechanical advantage that can allow the lifting of heavy weights.

Disadvantages - the pulley has to be securely anchored to support the mass being acted on, and the rope has to be strong and durable. A wheeled pulley needs to rotate smoothly, and a sliding (e.g. wooden) pulley should not abrade the rope. Also, the more pulleys you use, the more rope you need.

You need to consider the strength of the pulley's anchorage. If you try to raise a 40 lb load using a rope over a single pulley hung from the roof with the 2 legs of the rope parallel, the force on the anchorage will be 2 x 40 = 80 lbs.