lunes, 7 de marzo de 2011


The lever is simple machine made up of a stiff arm or arms that pivots or turns.  The point that a lever turns on is called the fulcrum. The load is the force of the thing you are trying to move.  Over 2000 years ago, a Greek scientist named Archimedes (ark a MEE dees) figured out how and why levers worked.  People had been using levers for a long time, but he was the first to explain them using math.  Legend credits Archimedes with saying, "With a big enough lever, you can move the world." 

The pulley is a simple machine made of a rope or chain wrapped around the wheel. A movable pulley reduces the amount of force needed to lift an object by object by increasing the distance over which the force is applied. The useful pulley is one of the earliest and simplest wheel devices.  Back in the eighth century B.C., the country that is now Syria may have discovered that a small wheel within a frame made it easier to pull up a heavy weight hanging from a rope running over the wheel.  Engineers in ancient times used this knowledge to their advantage in the construction of many monuments and temples.

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