A student produces two kinds of pulses with a stretched slinky on a laboratory table.
(a) She moves her hand up and down to send a single pulse along the slinky. Name the type of wave formed and explain the orientation of particle motion with respect to the direction of wave travel.
(b) She now pushes and pulls the end of the slinky along its length to send another pulse. Name this type of wave and explain how the particle motion differs from part (a).
(c) Explain why compressions and rarefactions are produced in the second case but crests and troughs are produced in the first case.
(d) Light from a torch and sound from a loudspeaker both reach a listener standing nearby. Identify whether each is a transverse or a longitudinal wave and justify each answer with one reason linked to their need for a medium or ability to be polarised.