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The Six Basic Machines of Physics A simple machine is a mechanical device that changes the direction or magnitude of a force. In general, they can be defined as the simplest mechanisms that use mechanical advantage (also called leverage) to multiply force. Usually the term refers to the six classical simple machines which were determined by renaissance scientists: Lever, Wheel and axle, Pulley, Inclined plane, Wedge, & Screw. A simple machine uses a single applied force to do work against a single load force. Ignoring friction losses, the work done on the load is equal to the work done by the applied force. The machine can increase the amount of the output force, at the cost of a proportional decrease in the distance moved by the load. The ratio of the output to the applied force is called the mechanical advantage. A lever is a simple machine that consists of a rigid object (often a bar of some kind) and a fulcrum (or pivot). Applying a force to one end of the rigid object causes it to pivot about the fulcrum, causing a magnification of the force at another point along the rigid object. There are three classes of levers, depending on where the input force, output force, and fulcrum are in relation to each other. Baseball bats, seesaws, wheelbarrows, and crowbars are types of levers. A wheel is a circular device that is attached to a rigid bar in its center. A force applied to the wheel causes the axle to rotate, which can be used to magnify the force (by, for example, having a rope wind around the axle). Alternately, a force applied to provide rotation on the axle translates into rotation of the wheel. It can be viewed as a type of lever that rotates around a center fulcrum. Ferris wheels, tires, and rolling pins are examples of wheels & axles. An inclined plane is a plane surface set at an angle to another surface. The wedge is often considered a specific type of inclined plane. A wedge is a doubleinclined plane (both sides are inclined) that moves to exert a force along the lengths of the sides. The force is perpendicular to the inclined surfaces, so it pushes two objects (or portions of a single object) apart. Axes, knives, and chisels are all wedges. The common "door wedge" uses the force on the surfaces to provide friction, rather than separate things, but it's still fundamentally a wedge. A screw is a shaft that has an in inclined groove along its surface. By rotating the screw (applying a torque), the force is applied perpendicular to the groove, thus translating a rotational force into a linear one. A pulley is a wheel with a groove along its edge, where a rope or cable can be placed. It uses the principle of applying force over a longer distance, and also the tension in the rope or cable, to reduce the magnitude of the necessary force. October 31, 2017 https://www.thoughtco.com/six-kinds-of-simple-machines-2699235 https://en.wikipedia.org/wiki/Simple_machine

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The Three Classes of Levers and Bell Crank with Mechanical Advantages A lever is a machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the location of fulcrum, load and effort, the lever is divided into three types. It is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the mechanical advantage of the lever. A class 1 lever has the load and the effort on opposite sides of the fulcrum, like a seesaw. A class 2 lever has the load and the effort on the same side of the fulcrum, with the load nearer the fulcrum. A class 3 lever does not have the mechanical advantage of class-one levers and class-two levers, so examples are less common. The effort and the load are both on the same side of the fulcrum, but the effort is closer to the fulcrum than the load, so more force is put in the effort than is applied to the load. A bellcrank linkage changes the direction of movement through 90°. A bell-crank linkage tends to look a little like an " L" or, as shown in the diagram below, a mirror image of an " L". By pulling (or pushing) the linkage in one direction, it creates a similar motion at the other end of the linkage. Machines and mechanical devices are used to create a mechanical advantage. Mechanical advantage helps us do work such as move heavy loads for a relatively small amount of effort. October 31, 2017 https://en.wikipedia.org/wiki/Lever , https://mechanicalinventors.wikispaces.com/Online+Resources

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