A student sketches a displacement–distance graph for a sound wave travelling in steel. She marks the positions of four consecutive compressions on the distance axis at 0cm, 2cm, 4cm and 5.8cm and concludes that the wavelength of the wave is 1.9cm.
(i) Identify and explain the error in the positions marked for the compressions.
(ii) Rewrite the correct set of equally spaced positions for four successive compressions.
(iii) After correcting the graph the average wavelength is found to be 2.0cm and the frequency of the source is 20kHz. Calculate the speed of sound in steel from these values.
(iv) Compare your answer with the typical value of 5950m/s for steel and suggest one possible reason for any difference.