SPECIFIC HEAT AND INTERNAL ENERGY:
Internal energy is not measurable. For solids and liquids in events without change of phase, specific internal energy is related to the event temperature change by the definition of definition of "specific heat."
c_sub_v.gif
Since specific heat is a function of temperature, the usual procedure is to use the mean value theorem of calculus to reduce the defining integral, then make a reasonable estimate of the average value of the specific heat.
Example - SPECIFIC HEAT MEASUREMENT: