The pressure and temperature ratios across a given portion of a shock wave in air are \(p_{2} / p_{1}=4.5\) and \(T_{2} / T_{1}=1.687\), where 1 and 2 denote conditions ahead of and behind the shock wave, respectively. Calculate the change in entropy in units of \((a)(\mathrm{ft} \cdot \mathrm{lb}) /\left(\mathrm{slug} \cdot{ }^{\circ} \mathrm{R}\right)\) and \( (b) \mathrm{J} /(\mathrm{kg} \cdot \mathrm{K})\).