A sound wave of frequency 500 Hz travels between two points $X$ and $Y$ separated by a distance of 600 m in a time of 2 s . The number of waves between the points $X$ and $Y$ are

The equation of a transverse wave propagating along a stretched string of length 80 cm is $y=1.5 \sin \left\{\left(5 \times 10^{-3} x\right)+20 t\right\}$, here ' $x$ ' and ' $y$ ' are in cm and the time ' $t$ ' is in second. If the mass of the string is 3 g , then the tension in the string is 80 cm

If a travelling wave is given by $y(x, t)=0.5 \sin (70.1 x-10 \pi t)$, where $x$ and $y$ are in metre the time $t$ is in second, then the frequency of the wave is

The path difference between two waves given by the equations

$y_1=a_1 \sin \left(\omega t-\frac{2 \pi x}{\lambda}\right)$ and $y_2=a_2 \sin \left(\omega t-\frac{2 \pi x}{\lambda}+\phi\right)$ is