Problem # p045

Internal Energy for Ideal Gas

For ideal gases the specific heat at constant volume, cv, is a function of temperature only. Experimental data for cv are often approximated by a 3rd order polynomial :

cv = a + b*T + c*T² + d*T³     T = temperature in [K]

Derive the equation for the change of internal energy [kJ/kg] for the ideal gas between two temperatures T1 and T2. Start with the definition of cv.