Assume that the flow of air through a given duct is isentropic. At one point in the duct, the pressure and temperature are \(p_{1}=1800 \mathrm{lb} / \mathrm{ft}^{2}\) and \(T_{1}=500^{\circ} \mathrm{R}\), respectively. At a second point, the temperature is \(400^{\circ} \mathrm{R}\). Calculate the pressure and density at this second point.