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The different types of levers in the human body. These levers consisting of First Class Lever, Second Class Lever, and a Third Class Lever. The list below describes such skeletal movements as normally are possible in particular joints of the human body.
A lever is a simple 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 locations of fulcrum, load, and effort, the lever is divided into three types.
In the example of a nail clipper on the right (a compound lever made of a class 2 and a class 3 lever), because the effort is applied vertically (that is, not perpendicular to the lever), distances to the respective fulcrums are measured horizontally, instead of along the lever. In this example, W/F is 7 + 1 / 1 × 6 / 6 + 2 = 6.
A crowbar with a curved chisel end to provide a fulcrum for leverage and a goose neck to pull nails. A crowbar, also called a wrecking bar, pry bar or prybar, pinch-bar, or occasionally a prise bar or prisebar, colloquially gooseneck, or pig bar, or in Australia a jemmy, [1] is a lever consisting of a metal bar with a single curved end and flattened points, used to force two objects apart or ...
Where a lever rotates continuously, it functions as a rotary second-class lever. The motion of the lever's end-point describes a fixed orbit, where mechanical energy can be exchanged. (see a hand-crank as an example.) In modern times, this kind of rotary leverage is widely used; see a (rotary) 2nd-class lever; see gears, pulleys or friction ...
For example, a bench vise consists of a lever (the vise's handle) in series with a screw, and a simple gear train consists of a number of gears (wheels and axles) connected in series. The mechanical advantage of a compound machine is the ratio of the output force exerted by the last machine in the series divided by the input force applied to ...
English: Within the human body there are 3 types of levers. The first class lever which can be seen, is located in the head. The second class lever is located within the leg. Finally, the third class lever is located in the arm.
Both first- and second-class lever designs exist; second-class is by far the more common. In the second-class lever design, the arm pivots below the rim. The brake shoe is mounted above the pivot and is pressed against the rim as the two arms are drawn together. In the first-class lever design, the arm pivots above the rim.