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A simple machine does work because it applies a force over a distance. If you are using the machine, you also do work, because you apply force to the machine to make it move. By definition, a simple machine has no source of energy except the immediate forces you apply. That means the only way to

get output work from a simple machine is to do input work on the machine.

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Simple machine :an unpowered

mechanical device that accomplishes a task with only one movement.

lever :a stiff structure that rotates

around a fixed point called a fulcrum.

gear: a rotating wheel with teeth that transfers motion and forces to other gears or objects.

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Lever: a stiff structure that rotates around a fixed point called a fulcrum.

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Like your arms and legs, your lower jaw is a lever. However, the lower jaw can work both as a second class and as a third class lever.

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The human body is a complex machine that includes a number of simple machines—levers. Levers provide the body with the ability to accomplish tasks. Your arms and legs, for example, work as levers to move and lift objects. In the last section, you learned that there are three classes of levers. Your limbs are examples of third class levers

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Joints and levers in the human body || 3D Animation||Education Biology

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The gear ratiois the ratio of output turns to input turns. The gear ratio canalso be calculated as the ratio of the number of teeth on the input gear versus the number on the output gear. The mechanical advantage of a pair of gears

is the inverse of the gear ratio

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Mechanical advantage

is the ratio of output force to input force. If the mechanical advantage is greater than 1, the output force is bigger than the

input force

A mechanical advantage less than 1 means the output force is smaller than the input force. What does it mean when mechanical advantage equals 1? In this case, the output force equals the

input force

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Gears can transfer motion and force when the teeth of one gear press on the teeth of another gear as each gear rotates around a shaft.

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Machine: a device with moving parts that work together to accomplish a task.

Input: forces, energy, or power supplied to make a machine accomplish a task.

Output: forces, energy, or power provided by the machine.

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Tension in ropes

and strings .Ropes and strings carry tension

forces along their length. The tension is the same at every point in a rope. If the rope is not moving, its tension is equal to

the force pulling on each end (below). Ropes or strings do

not carry pushing forces