Heat capacity properties are often prefixed with the term "specific". International standards now recommend that specific heat capacity always refer to division by mass. The units for the specific heat capacity are formula_7. In chemistry, heat capacity is often specified relative to one mole, the unit of amount of substance, and is called the molar heat capacity. It has the unit formula_8. For some considerations it is useful to specify the volume-specific heat capacity, commonly called volumetric heat capacity, which is the heat capacity per unit volume and has SI units formula_9. This is used almost exclusively for liquids and solids, since
Action (physics) in time and space. Action has the dimensions of [energy]⋅[time], and its SI unit is joule-second, which is identical to the unit of angular momentum. In classical physics, the term "action" has a number of meanings. Most commonly, the term is used for a functional formula_2 which takes a function of time and (for fields) space as input and returns a scalar. In classical mechanics, the input function is the evolution q("t") of the system between two times "t" and "t", where q represents the generalized coordinates. The action formula_3 is defined as the integral of the Lagrangian "L" for