An engine that operates on a Brayton cycle uses air as its working substance, compressing ambient air initially at a pressure of \(1.0 \mathrm{~atm}\) to \(6.0 \mathrm{~atm}\).

(a) What is the engine's pressure ratio?

(b) If the heat capacity ratio \(\gamma=C_{P} / C_{V}\) is 1. 40 for air, what is the engine's efficiency?

(c) At high altitudes, \(\gamma=1.44\) and the ambient air pressure is \(0.40 \mathrm{~atm}\). If the engine compresses this air to \(4.8 \mathrm{~atm}\), what is its efficiency now?