The word lever entered the English language around the 1300s, but its roots stretch back to a Proto-Indo-European stem meaning light, easy, or nimble. This linguistic history reveals that the concept of the lever was originally tied to the idea of making things lighter or easier to move. Autumn Stanley argues that the digging stick, used by prehistoric women, was the very first lever, positioning them as the true inventors of this technology. The earliest cultural evidence of the lever mechanism dates back to ancient Egypt, where it was used in a simple balance scale. In Mesopotamia, which is modern Iraq, the shadouf, a crane-like device using a lever mechanism, was invented to lift water. In ancient Egypt, workmen used the lever to move and uplift obelisks weighing more than 100 tons. This is evident from the recesses in the large blocks and the handling bosses that could not be used for any purpose other than for levers.
Archimedes And The World
The earliest remaining writings regarding levers date from the third century BC and were provided by the Greek mathematician Archimedes. He famously stated that if given a lever long enough and a fulcrum on which to place it, he could move the world. The Greek usually attributed to Archimedes does not include details about the length of the lever or the fulcrum, yet the statement has given rise to the phrase an Archimedean lever being adopted for use in many instances. This phrase is used not just regarding mechanics, including abstract concepts about the successful effect of a human behavior or action intended to achieve results that could not have occurred without it. The law of the lever, as discussed by Archimedes, shows that if the distance from the fulcrum to where the input force is applied is greater than the distance from the fulcrum to where the output force is applied, then the lever amplifies the input force. If the opposite is true, the lever reduces the magnitude of the input force.Three Classes Of Motion
Levers are classified by the relative positions of the fulcrum, effort, and resistance. It is common to call the input force effort and the output force load or resistance. This allows the identification of three classes of levers by the relative locations of the fulcrum, the resistance and the effort. Class one levers have the fulcrum located between the effort and the resistance. Examples include a seesaw, a crowbar, a pair of scissors, a balance scale, a pair of pliers, and a claw hammer. With the fulcrum in the middle, the lever's mechanical advantage may be greater than, less than, or even equal to one. Class two levers have the resistance located between the effort and the fulcrum. The effort is applied on one side of the resistance and the fulcrum is located on the other side. Examples include a wheelbarrow, a nutcracker, a bottle opener, a wrench, a pair of bellows, and the brake pedal of a car. Since the load arm is smaller than the effort arm, the lever's mechanical advantage is always greater than one. It is also called a force multiplier lever. Class three levers have the effort located between the resistance and the fulcrum. The resistance is applied on one side of the effort and the fulcrum is located on the other side. Examples include a hoe, a pair of tweezers, a hammer, a pair of tongs, a fishing rod, and the mandible of a human skull. Since the effort arm is smaller than the load arm, the lever's mechanical advantage is always less than one. It is also called a speed multiplier lever.