When the listener moves towards stationary source with velocity ' $\mathrm{V}_1$ ', the apparent frequency of emitted note is ' $F_1$ '. When observer moves away from the source with velocity ' $\mathrm{V}_1$ ', apparent frequency is ' $F_2$ '. If V is the velocity of sound in air and $\frac{F_1}{F_2}=2$ then $\frac{V}{V_1}$ is

When the string is stretched between two rigid supports, under certain tension and vibrated

A musical instrument X produces sound waves of frequency n and amplitude A. Another musical instrument $Y$ produces sound waves of frequency $\frac{n}{3}$. The waves produced by $x$ and $y$ have equal energies. The amplitude of waves produced by Y will be

A stationary wave is formed having 3 nodes along the length of the string 90 cm . The wavelength of the wave is