Simple machine lever

There is generally considered to be five distinct simple machines lever, wedge, wheel and axle, pulley, and screw. The transmission of energy by these simple machines is so basic that people use them with little understanding of the physical principles involved. Most learn their use intuitively, through experience, and consider their application just plain common sense. 

Applied physics is of necessity the oldest of all practical sciences, dating back to the first artificial use of an object by an early hominid. The basic practices have been in use by builders and designers for many thousands of years. With the development of mathematics and measurement, the practice of applied physics has grown apace, relying as it still does upon the application of basic concepts of vector properties (force, momentum, velocity, weight, moment of inertia) and the principles of simple machines (lever, ramp, pulley). 

In the transmission of energy by these simple machines, the conseiwation law always applies The work input equals the work output. Wlien work is done by a system, energy is transferred out of it and when work is done on a system, energy is transferred into it. When two objects interact by way of a machine (e.g. a lever), the work out of one object equals the work into the other. The work done by a person forcing one end of a lever downward equals the work done lifting a load at the other end as the lever moves upward. In any practical situation, the frictional forces resisting motion will always increase the amount of force (and work) required to do ajob. 

The amount of work done on an object is determined by the force exerted on it multiplied by the distance it moves in the direction of the force. Therefore the key to figuring out how much the force is magnified by a simple machine is to compare distances moved. For example, if the end of a lever under a stone weighing 2,000 newtons moves upward 1 meter, the amount of work done lifting the stone is 1 meter X... 

A lever is a simple machine that consists of a rigid bar supported at one point, known as the fulcrum. A force called the effort force is applied at one point on the lever in order to move an object, known as the resistance force, located at some other point on the lever. A common example of the lever is the crow bar used to move a heavy object such as a rock. To use the crow bar, one end is placed under the bar, which is supported at some point (the fulcrum) close to the rock. A person then applies a force at the opposite end of the crow bar to lift the rock. A lever of the type described here is a first-class lever because the fulcrum is placed between the applied force (the effort force) and the object to be moved (the resistance force). 

A pulley is a simple machine consisting of a grooved wheel through which a rope runs. The pulley can be thought of as a kind of lever if one thinks of the grooved wheel as the fulcrum of the lever. Then the effort force is the force applied on one end of the pulley rope, and the resistance force is the weight that is lifted at the opposite end of the pulley rope. 

A second variation of the lever is the simple machine known as a wheel and axle. A wheel and axle cm-sists of two circular pieces of drffermt si2BS attached to each other. The larger circular piece is the wheel in the stenr, and the mraller circular piece is the axle. One of the circular pieces can be considered as the effort arm of the lever and the second, the resistance arm. The place at whichthe two are joined is the fulcrum of the stem. 

Compound machines are two or more simple machines working together. A wheelbarrow is an example of a complex machine. It uses a lever and a wheel and axle. Machines of all types ease workload by changing the size or direction of an applied force. The amount of effort saved when using simple or complex machines is called mechanical advantage or MA. 

A simple machine is a basic device used to make work easier. Work is the transfer of energy from one physical system to another. During this process, energy is not created, only transferred. There are six simple machines inclined plane, wedge, screw, lever, wheel and axle, and pulley. We discuss each simple machine separately in this chapter. If we combine two or more simple machines so that they function together to make work easier, the device is called a compound machine. A wheelbarrow is an example of a compound machine it incorporates two simple machines (the lever and the wheel and axle). 

FIGURE 10-5 The lever is a very useful simple machine. It provides a mechanical advantage to help with work. 

In Unear motion, an object moves along a straight line such as that done by a grocery store checkout conveyor. The lever is a simple machine that provides Unear motion. 

There are six simple machines inclined plane, wedge, lever, pulley, screw, and wheel and axle. 

B.C.E. Lever Described by Archimedes, the lever is a simple machine that allows one to deliver a larger force to a load than the force with which one pushes on the lever. 

Since fluid power is efficiently transmitted and controlled, it gives freedom in designing a machine. The need for gear, cam, and lever systems is eliminated. Fluid power systems can provide infinitely variable speed, force and direction control with simple, reliable elements. 

Most modern machines can be traced back to the five basic machines described by the Greek inventor Hero of Alexandria who lived at about the time of Christ. The machines described by him were the wedge, the screw, the wheel and axle, the pulley, and the lever. Originally they were used for simple purposes, to raise water and to move objects which man alone could not lift, but today their principles are of fundamental importance to our scientific understanding of mechanics. Let us now consider some fundamental mechanical principles and calculations. 

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