Editing Mechanical advantage (section)

=== Ideal mechanical advantage ===
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The ''ideal mechanical advantage'' (IMA), or ''theoretical mechanical advantage'', is the mechanical advantage of a device with the assumption that its components do not flex, there is no friction, and there is no wear.  It is calculated using the physical dimensions of the device and defines the maximum performance the device can achieve.

The assumptions of an ideal machine are equivalent to the requirement that the machine does not store or dissipate energy; the power into the machine thus equals the power out.  Therefore, the power ''P'' is constant through the machine and force times velocity into the machine equals the force times velocity out{{mdash}}that is,
:<math> P = F_\text{in}v_\text{in}= F_\text{out}v_\text{out}. </math>

The ideal mechanical advantage is the ratio of the force out of the machine (load) to the force into the machine (effort), or
:<math>\mathit{IMA} = \frac {F_\text{out}} {F_\text{in}}. </math>
Applying the constant power relationship yields a formula for this ideal mechanical advantage in terms of the speed ratio:
:<math>\mathit{IMA} = \frac {F_\text{out}} {F_\text{in}} = \frac {v_\text{in}} {v_\text{out}}.</math>

The speed ratio of a machine can be calculated from its physical dimensions. The assumption of constant power thus allows use of the speed ratio to determine the maximum value for the mechanical advantage.