Speed of Longitudinal Waves #8211; (i) If the medium is solid in the form of a long rod, then v = √Y/ρ Where, Y is the Young s modulus of long rod and ρ is the density of long solid rod. (ii) In a liquid medium, v = √B/ρ where, B is the bulk modulus of the liquid and ρ is the density of the liquid medium. (iii) According to Newton s formula, speed of sound in a gas is obtained by isothermal process, v = √P/ρ where, p is pressure and ρ is density of the gas.