Pulleys A pulley is a wheel with a grooved rim, and there may be several of these mounted in a framework called a block. The effort is applied to a rope which passes over the  pulleys.

The lever

The lever The simplest form of lever in common use is a steel rod known as a crowbar, but the term lever may be applied to any rigid body which is pivoted about a point called the fulcrum. Levers are based on the principle of moments, which was discussed in chapter 6. A force called the effort …

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Machines Most people think of a machine as being a more or less complicated piece of mechanism which includes gear wheels, levers, screws, and so on. But however complex a machine may appear to be, its various parts can always be shown to be applications of a limited number of basic mechanical principles. Essentially, a machine is any device …

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