A progressive wave of frequency 500Hz is travelling with a velocity of 360 m`//` s. How far part are two points `60^(@)` out of phase ?

Explanation

We know that for a wave `v = flambda`,
So `lambda = (u)/(f) = (360)/(500)` = 0.72
Now as in a wave path difference isrelated to phase difference by the relation,
phase difference
`Deltaphi = (2pi)/(lambda)` (path difference Deltax)
Here, phase difference
`Deltaphi = 60^(@) = (pi//180)xx60 = (pi//3) rad`
So path difference
`Deltax = (lambda)/(2pi)(Deltaphi) = (0.72)/(2pi)xx(pi)/(3)` = 0.12 m.