$A$ progressive wave of frequency $400 \ Hz$ is travelling with velocity $336 \ m/s$. How far apart are the two points on a wave which are $60^{\circ}$ out of phase (in $m$)?

Which of the following statements is incorrect during the propagation of a plane progressive mechanical wave?

The diagram below shows an instantaneous position of a string as a transverse progressive wave travels along it from left to right. Which one of the following correctly shows the direction of the velocity of the points $1$, $2$ and $3$ on the string?

$A$ progressive wave of frequency $50\text{ Hz}$ is travelling with velocity $350\text{ m/s}$ through a medium. The change in phase at a given time interval of $0.01\text{ s}$ is

The equation of a plane progressive wave is given by $y = 0.6 \sin 2\pi (t - x/2)$. On reflection from a denser medium,its amplitude becomes $2/3$ of the amplitude of the incident wave. The equation of the reflected wave is:

The equation of a progressive wave is given by $y = A \cos 240(t - x/12)$,where $t$ is the time in seconds and $x$ is the distance in meters. The phase difference (in radians) between two positions $0.5 \, m$ apart is: