The fundamental frequency of an air column in a pipe closed at one end is 150 Hz . If the same pipe is open at both the end, the frequencies produced in Hz are

When the observer moves towards a 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 $\mathrm{V}_1$, the apparent frequency is $\mathrm{F}_2$. If V is the velocity of sound in air and $F_1 / F_2=2$ then $V / V_1$ is equal to

A musical instrument ' P ' produce sound waves of frequency ' $n$ ' and amplitude ' $A$ '. Another musical instrument ' $Q$ ' produces sound waves of frequency ' $\frac{\mathrm{n}}{4}$ ' The waves produced by ' P ' and ' $Q$ ' have equal energies. If the amplitude of waves produced by ' P ' is ' $\mathrm{A}_{\mathrm{p}}$ ', the amplitude of waves produced by ' $Q$ ' will be