Answer the following questions about the propagation of sound in different media:
(i) State which elastic modulus is relevant for determining the speed of sound in (a) a brass rod and (b) liquid nitrogen.
(ii) Explain qualitatively, with reference to typical values of elastic modulus and density, why sound generally travels faster in solids than in liquids and faster in liquids than in gases.
(iii) Illustrate your explanation in (ii) by choosing reasonable numerical values of modulus and density for a solid, a liquid and a gas, and comparing the corresponding speeds of sound obtained from the relevant formula.