The phase difference between two points separated by $0.8 m$ in a wave of frequency $120 Hz$ is ${90^o}$. Then the velocity of wave will be ............ $\mathrm{m/s}$

A train is moving towards a stationary observer. Which of the following curve best represents the frequency received by observer $f$ as a function of time ?

Equation of a plane progressive wave is given by $y = 0.6\sin 2\pi \left( {t - \frac{x}{2}} \right)$. 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 displacement of two waves are given as ${y_1} = 10\,\sin \,\left( {3\pi t\, + \,\pi /3\,} \right)$ , ${y_2} = 5\,\left( {\sin \,3\pi t + \,\sqrt 3 \,\cos \,3\pi t} \right)$ , then what is the ratio of their amplitude 

In a sinusoidal wave, the time required for a particular point to move from maximum displacement to zero displacement is $0.170 \,s$. The frequency of wave is ........ $Hz$

Two monoatomic ideal gases $1$ and $2$ of molecular masses $M_1$ and $M_2$ respectively are enclosed in separate containers kept a the same temperature. The ratio of the speed of sound in gas $1$ to that in gas $2$ is