Two wires of identical length, diameter and material are stretched on a sonometer box. The ratio of the tension is $1 : 4.$ The ratio of their fundamental frequency is

Two tuning forks with națural frequencies $170 \mathrm{Hz}$ each move relative to a stationary observer. One fork moves away from the observer while the other moves towards him at the same speed. The observer hears beats of frequency $2 \mathrm{Hz}.$ Speed of the tuning fork is $n \mathrm{m} {\mathrm{s}}^{-1}.$ Write the value of $n$ to the nearest ineteger.

(velocity of sound in air is $340 \mathrm{m} {\mathrm{s}}^{-1}$)

A source is oscillating between $A$ and $C$ with its position varying with time as $y=900 \cos \left(\frac{\pi t}{6}\right),$ where $y$ is in metre. An observer is situated at a distance $12 \mathrm{m}$ along the perpendicular bisector of $AC.$ Frequency emitted by source is $300 \mathrm{Hz}.$ Approximate frequency observed by observer when source is at $O$ is $5n \mathrm{Hz}.$ Value of $n,$ is [Velocity of sound in air $=300 \mathrm{m} {\mathrm{s}}^{-1}$]