Answer the questions that follow to clarify the relationship between wavelength, frequency and speed for both transverse and longitudinal mechanical waves.
(i) Using the idea that one wavelength is covered by the wave in one time period, show that v=fλ.
(ii) Draw a neat, labelled diagram of one wavelength for (a) a transverse wave on a stretched string and (b) a longitudinal wave in air, marking crest–trough or compression–rarefaction appropriately.
(iii) From your diagrams, explain how energy is transported in each case without the medium itself advancing along the direction of wave propagation.