Given below are some functions of `x` and `t` to represent the displacement (transverse or longitudinal) of an elastic wave. State which of these represent `(i)` a travelling wave, `(ii)` a stationary wave or `(iii)` none at all
(a) `y = 2 cis (3x) sin (10t)`
(b) `y =`
(c) `y = 3 sin (5x - 0.5t) + cos (5x - 5t)`
(d) `y = cosx sin t + cos 2x sin 2t`

Answer

(a) Stationary wave.
(b) Unacceptable funcation for any wave.
(c) Travelling harmonic wave.
(d) Superposition of two stationary waves.