Simple Machines - Pulley power
Pulley power
A pulley consists of a rope or other cord pulled over a steadied wheel. At one end of the rope is the object or load to be lifted; the other end is where the force is applied.
A single, fixed pulley changes the direction of a force. The force needed to lift the load still equals the weight of the load, yet it can feel easier if a person is pulling down instead of pushing up. Using two or more pulleys connected together can decrease the amount of effort needed to lift the same load. If using two pulleys, the rope leading to each individual pulley can hold half as much weight. With the load weighing half as much, a person need apply only half the force. The tradeoff is that the rope needs to be pulled twice the distance. The force is cut in half but the distance the rope must be pulled has doubled.
[The entire page is 171 words long]
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