In air at 25 °C, a longitudinal sound wave of small amplitude propagates along the positive x-axis. The speed of sound under these conditions is 340 m s−1. The frequency of the wave is 340 Hz and the amplitude of the excess pressure variation is 0.060 Pa. At x=0 and t=0, the excess pressure is zero and is increasing with time.
(a) Calculate the wavelength and the angular frequency of the wave.
(b) Write an expression for the excess pressure p(x,t) (in pascals) as a function of position x (in metres) and time t (in seconds) that satisfies the given initial condition.
(c) Using your expression, find the earliest time after t=0 when the excess pressure at x=0 again becomes zero.