There are several ways to calculate the speed of sound cs in a gas, for example C_,/7'R;T 5 M v where \"y is the adiabatic coefficient of the gas, R is the ideal gas constant, T is the temperature in Kelvin, and M is the molar mass. Find the speed of sound in air at T = 0C and at T = 20C, use 7 = 1.4, M = 28.97 g/mol, and 0C = 273.15 K. The speed of sound in air at 0C, c1 = Units . The speed of sound in air at 20C, c2 = Units . A convenient approximate way to find the speed of sound at low temperatures (note that the temperature must be small in Celsius, not in Kelvin: T(in C)