One approximation of this quantity involves taking the limit of the integral [read slowly] “x to the fourth times e to the x, [pause] over the quantity e to the x minus one squared” in a model of this quantity that sets a namesake temperature proportional to the cube root of “six pi squared times number density”. Einstein’s model (10[1])of this quantity with a lattice of 3D QHOs fails to account (10[1])for the cubic temperature dependence of this quantity observed in the Debye (“duh-BYE”) model. This quantity’s high-temperature value is three times the ideal gas constant according to the Dulong–Petit law. The adiabatic index is the ratio between this quantity’s constant-volume (10[1])and constant-pressure forms. For 10 points, one calorie (10[1])per (10[2])gram per degree Kelvin is water’s value (10[1])of what quantity, which measures how much heat it takes to increase an object’s temperature? ■END■