On a stretched spring, a sinusoidal longitudinal wave of amplitude 2.5 mm travels to the right with a speed of 18 m s−1. The frequency of oscillation is 15 Hz. The origin is chosen to be a point which, at t=0, is at maximum positive displacement.
(a) Find the wavelength of the wave.
(b) Write the equation that gives the longitudinal displacement s(x,t) (in millimetres) of an element of the spring as a function of position x (in metres) and time t (in seconds).
(c) Express the same equation obtained in part (b) in terms of the time period T instead of the frequency.