A vehicle starts from rest and accelerates along straight path at $2 \mathrm{~m} / \mathrm{s}^2$. At the starting point of the vehicle, there is a stationary electric siren. How far has the vehicle nearly gone when the driver hears the siren at $94 \%$ of its value when the vehicle was at rest?

(speed of sound $=220 \mathrm{~m} / \mathrm{s}$ )

A pipe open at both ends of length 1.5 m is dipped in water at one end such that $2^{\text {nd }}$ overtone of vibrating air column is resonating with a tuning fork of frequency 330 Hz . The length of the pipe immersed in water is (Speed of sound in air $=330 \mathrm{~m} / \mathrm{s}$ ) (Neglect end correction)

Two uniform wires of same material are vibrating under the same tension. If the $1^{\text {st }}$ overtone of $1^{\text {st }}$ wire is equal to the $2^{\text {nd }}$ overtone of $2^{\text {nd }}$ wire and radius of $1^{\text {st }}$ wire is twice the radius of $2^{\text {nd }}$ wire, the ratio of length of $1^{\text {st }}$ wire to that $2^{\text {nd }}$ wire is

An observer on sea-coast counts 45 waves in one minute. If the wavelength of the waves is 7 m , then the velocity of the waves will be