Foot-pound, definition

Both of these are expressed in foot-pounds. Sometimes a substitution of a definite value of n in one or die other of these equations leads to an indeterminate for example, with the isothermal,... 

In the United States of America, English units of measurement are still in common use. The inch (in) has been redefined to equal exactly 0.0254 m. The foot (ft) is 12 inches and the mile (mi) is 5280 feet. The pound (lb) is equal to 0.4536 kg (not an exact definition good to four significant digits). 

The definition of density establishes its units. Mass is commonly measured in grams (g) volume is measured in cubic centimeters (cm ). Therefore, according to Equation 3.9 and the mass-per-unit-volume definition, the units of density are grams per cubic centimeter, g/cm - Liquid densities are often given in grams per milliliter, g/mL. (Recall that one milliliter is exactly one cubic centimeter by definition.) There are, of course, other units in which density can be expressed, but they all must reflect the definition in terms of mass volume. Examples are grams/liter, usually used for gases because their densities are so low, and the USCS pounds/cubic foot. 

James Joule published his definitive work related to the first law of thermodynamics in 1850. He stated that "the quantity of heat capable of increasing the temperature of one pound of water by 1 °F requires for its evolution the expenditure of a mechanical force represented by the fall of 772 lb through the space of one foot." Validate this statement by relating it to information given in this text. 

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