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Ideal Mechanical Advantage

The ideal mechanical advantage (IMA) is always different from the mechanical advantage because of friction. Friction slows down the MA. The work of friction is energy that is converted to thermal energy. A lever is an example of a MA that is close to the IMA. An inclined plane is an example of a mechanical advantage that is far from its ideal mechanical advantage.

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A mechanical advantage, some of the work done by the input force is converted to thermal energy by the friction in the machine. Therefore, the work done by the output force is less than the work done by the input force. There is no friction in ideal mechanical advantage therefore no energy is converted to thermal energy. The mechanical advantage of a machine with no friction is called the ideal mechanical advantage. The ideal mechanical advantage can be calculated by finding the ratio between the distance over the input force that is pressed on the machine (Din) and the distance over which the output force is exerted on the object (Dout).

How to calculate
IMA=din/dout
Ideal mechanical advantage = input distance/output distance

Ideal mechanical advantage less than one.
Sometimes the IMA is less than one and the output distance is greater than the input distance. This means the speed of the input is lower then the speed of the output. When an increase in speed of motion is required, an IMA of less than one is sometimes needed. Some examples of machines that have a mechanical advantage less than one are hockey sticks, baseball bats, and garden rakes. Also class three and sometimes class one levers have a MA less than one.

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Ideal mechanical advantage greater than one.
When the IMA is greater than one it means that the input distance is greater than the output distance. This mean the speed of the input is higher then the speed of the output. Some examples of machines with the mechanical advantage greater then one are a crow bar, car jack, and a hammer. Class two and sometimes class one levers have a MA greater than one.

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