(c) When a substance is heated and expands, it does work against the atmosphere. This work contributes partly (but not fully) to the difference between the specific heat capacity at constant pressure Cp and the specific heat capacity at constant volume cy for that substance. Show explicitly that the difference between the specific heat capacity at constant pressure Cp and the specific heat capacity at constant volume cy that results from the above that is, the work against the atmosphere) is where P is the pressure, is the expansivity of the substance and p is the density of the substance. [17 marks] PE P