Mechanical efficiency explained

η ) is a dimensionless number between 0 and 1 that is the ratio between the power output of the machine and the power input^[1]

$$\backslash eta\; =\; \backslash frac$$

Since a machine does not contain a source of energy, nor can it store energy, from conservation of energy the power output of a machine can never be greater than its input, so the efficiency can never be greater than 1.

All real machines lose energy to friction; the energy is dissipated as heat. Therefore, their power output is less than their power input

$$\backslash text\; =\; \backslash text\; -\; \backslash text$$

Therefore, the efficiency of all real machines is less than 1. A hypothetical machine without friction is called an ideal machine; such a machine would not have any energy losses, so its output power would equal its input power, and its efficiency would be 1 (100%).

For hydropower turbines the efficiency is referred to as hydraulic efficiency.^{[2] [3]}

See also

• Mechanical advantage
• Thermal efficiency
• Electrical efficiency
• Internal combustion engine
• Electric motor
• Velocity ratio

Notes and References

1. Web site: Mechanical efficiency. Encyclopedia Britannica . 2017-06-08 . . 2017-06-08.
2. Continuous Efficiency Measurements on Hydro Power Plants . PhD . 2016 . Erik Jacques . Wiborg . Norway . Institutt for energi og prosessteknikk.
3. IEC standard 60041