In the equation shown, what does (gamma) represent?

• A. The heat capacity ratio
• B. The viscosity
• C. The density
• D. The thermal conductivity

Answer: (A)

Gamma is the ratio of a gas’s specific heats at constant pressure and constant volume, Cp/Cv. This dimensionless value shows how energy added as heat splits between raising temperature and doing work when the gas is compressed or expanded. It governs many gas-dynamic relationships, such as the adiabatic pressure–volume relation pV^gamma = constant and the expression for the speed of sound in an ideal gas, a = sqrt(gamma * R * T). That’s why gamma is described as the heat capacity ratio rather than relating to viscosity, density, or thermal conductivity. The ratio depends on molecular structure and temperature (for air around room temp gamma ≈ 1.4; for monatomic gases about 5/3).