All Problems

Elastic Waves. Acoustics.

Problem 4.153

A plane elastic wave ξ=acos(ωtkx)\xi=a \cos (\omega t-k x) propagates in a medium KK. Find the equation of this wave in a reference frame KK^{\prime} moving in the positive direction of the xx axis with a constant velocity VV relative to the medium K.K . Investigate the expression obtained.

Reveal Answer
ξ=acos[(1V/v)ωtkx], where v=ω/k\xi=a \cos \left[(1-V / v) \omega t-k x^{\prime}\right], \text { where } v=\omega / k