clc;clear all;
%% Problem 5

%N2 Properties
R = 296.8; %N2 J/kg*K
Tv = 3521; %K, characteristic vibrational temp
T1 = 300; %K
T2 = 3000; %K

% Since density is constant:
density_ratio = 1;

%% Calorically Perfect Gas
Cv_cpg = (5/2)*R;
Cp_cpg = Cv_cpg + R;
gamma_cpg = Cp_cpg/Cv_cpg;

entropy_change_cpg = Cv_cpg*log(T2/T1) - R*log(density_ratio);
disp(['Assuming CPG, the change in entropy is: ', num2str(entropy_change_cpg), ' J/K', newline]);
%% Thermally Perfect Gas
theta_v1 = Tv/(2*T1);
theta_v2 = Tv/(2*T2);
entropy_change_tpg = R*(log(((T2/T1)^1/(gamma_cpg-1))*density_ratio) + ((theta_v2*coth(theta_v2)) + log(sinh(theta_v1)/sinh(theta_v2)) - ((theta_v1*coth(theta_v1)))));
disp(['Assuming TPG, the change in entropy is: ', num2str(entropy_change_tpg), ' J/K']);