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unusual facts about degree Fahrenheit



ISO 31-4

Annex A of ISO 31-4 lists units of heat based on the foot, pound and second and some other units, including the degree Rankine, degree Fahrenheit, British thermal unit and others.


see also

False precision

Modern studies show that none of these values is accurate to one tenth of a degree Fahrenheit, even for the hypothetical average person (see Human body temperature).

Mechanical equivalent of heat

In particular Joule had experimented on the amount of mechanical work generated by friction needed to raise the temperature of a pound of water by one degree Fahrenheit and found a consistent value of 772.24 foot pound force (4.1550 J·cal-1).

Thermodynamic temperature

1859: William John Macquorn Rankine (1820–1872) proposed a thermodynamic temperature scale similar to William Thomson's but which used the degree Fahrenheit for its unit increment.

The Rankine scale, using the degree Fahrenheit as its unit interval, is still in use as part of the English Engineering Units in the United States in some engineering fields.