The transverse displacement of a medium is described by the wavefunction y(x, t) asin(wt ka) where t is time and x is the position along the medium. (a) define the terms a, w and k, stating appropriate units (b) state the direction of propagation of the wave (c) the wave is reflected from a boundary give an expression for the reflected wavefunction when the propagation velocity (i) increases at the boundary; (ii) decreases at the boundary c2. a 1.15 khz sound source is accelerated away from a microphone such that its velocity rises linearly from 0 to 66ms1 in 1.1s. the speed of sound in air is 344ms. calculate (a) the lowest frequency detected by the microphone; (b) the time taken for the detected frequency to fall below 1.0 khz. [hint: neglect the time it takes for the sound to travel from the source to the microphone.]