The closed and open organ pipe have same length and when they are vibrating simultaneously in first overtone produce 3 beats. The length of open pipe is made $\left(\frac{1}{3}\right)^{\mathrm{rd}}$ and that of closed pipe is made 3 times the original, the number of beats produced will be (Neglect end correction)

The length of closed and open pipe is same. The ratio of frequency of $\mathrm{n}^{\text {th }}$ overtone for closed pipe to that of open pipe is (Neglect end correction)

The frequency of a stretched uniform wire of length $L$ under tension is in resonance with the fundamental frequency of a closed pipe of same length. If the tension in the wire is increased by 8 N , it is in resonance with the first overtone of the same closed pipe. The initial tension in the wire is

When an observer moves towards a stationary source with velocity ' $\mathrm{V}_1$ ', the apparent frequency of emitted note is ' $\mathrm{F}_1$ '. When observer moves away from stationary source with velocity ' $\mathrm{V}_1$ ' the apparent frequency is ' $\mathrm{F}_2$ '. If ' v ' is velocity of sound in air and $\frac{\mathrm{F}_1}{\mathrm{~F}_2}=2$, then $\frac{\mathrm{V}}{\mathrm{V}_1}$ is equal to