172956 A man standing far from a hill, fires a gun and hears its echo after $4 \mathrm{~s}$. Later he moves $320 \mathrm{~m}$ from his initial position away from the hill and fires the gun again and now he hears the echo after $6 \mathrm{~s}$. Then the velocity of the sound in air is

172957 A police car with a siren of frequency $8 \mathrm{kHz}$ is moving with uniform velocity of $20 \mathrm{~m} / \mathrm{sec}$ towards a tall building which reflects the sound waves. If speed of sound in air be $320 \mathrm{~m} / \mathrm{sec}$, the frequency of siren heard by car driver is.

172958 A whistle of frequency $540 \mathrm{~Hz}$ rotates along a circle of radius $2 \mathrm{~m}$ an angular speed of $15 \mathrm{rad}$ $\mathrm{s}^{-1}$. The difference in maximum and minimum frequencies heard by a listener at some distance and at rest with respect to the centre of the circle is.
(Speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

172959 A train sounds its whistle as it approaches an observer standing at a point near the track. The observer measures a frequency of $216 \mathrm{~Hz}$ as the train approaches and a frequency of $\mathbf{1 8 4}$ $\mathrm{Hz}$ as the train leaves. What is the frequency of its whistle?

172956 A man standing far from a hill, fires a gun and hears its echo after $4 \mathrm{~s}$. Later he moves $320 \mathrm{~m}$ from his initial position away from the hill and fires the gun again and now he hears the echo after $6 \mathrm{~s}$. Then the velocity of the sound in air is

172957 A police car with a siren of frequency $8 \mathrm{kHz}$ is moving with uniform velocity of $20 \mathrm{~m} / \mathrm{sec}$ towards a tall building which reflects the sound waves. If speed of sound in air be $320 \mathrm{~m} / \mathrm{sec}$, the frequency of siren heard by car driver is.

172958 A whistle of frequency $540 \mathrm{~Hz}$ rotates along a circle of radius $2 \mathrm{~m}$ an angular speed of $15 \mathrm{rad}$ $\mathrm{s}^{-1}$. The difference in maximum and minimum frequencies heard by a listener at some distance and at rest with respect to the centre of the circle is.
(Speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

172959 A train sounds its whistle as it approaches an observer standing at a point near the track. The observer measures a frequency of $216 \mathrm{~Hz}$ as the train approaches and a frequency of $\mathbf{1 8 4}$ $\mathrm{Hz}$ as the train leaves. What is the frequency of its whistle?

172956 A man standing far from a hill, fires a gun and hears its echo after $4 \mathrm{~s}$. Later he moves $320 \mathrm{~m}$ from his initial position away from the hill and fires the gun again and now he hears the echo after $6 \mathrm{~s}$. Then the velocity of the sound in air is

172957 A police car with a siren of frequency $8 \mathrm{kHz}$ is moving with uniform velocity of $20 \mathrm{~m} / \mathrm{sec}$ towards a tall building which reflects the sound waves. If speed of sound in air be $320 \mathrm{~m} / \mathrm{sec}$, the frequency of siren heard by car driver is.

172958 A whistle of frequency $540 \mathrm{~Hz}$ rotates along a circle of radius $2 \mathrm{~m}$ an angular speed of $15 \mathrm{rad}$ $\mathrm{s}^{-1}$. The difference in maximum and minimum frequencies heard by a listener at some distance and at rest with respect to the centre of the circle is.
(Speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

172959 A train sounds its whistle as it approaches an observer standing at a point near the track. The observer measures a frequency of $216 \mathrm{~Hz}$ as the train approaches and a frequency of $\mathbf{1 8 4}$ $\mathrm{Hz}$ as the train leaves. What is the frequency of its whistle?

172956 A man standing far from a hill, fires a gun and hears its echo after $4 \mathrm{~s}$. Later he moves $320 \mathrm{~m}$ from his initial position away from the hill and fires the gun again and now he hears the echo after $6 \mathrm{~s}$. Then the velocity of the sound in air is

172957 A police car with a siren of frequency $8 \mathrm{kHz}$ is moving with uniform velocity of $20 \mathrm{~m} / \mathrm{sec}$ towards a tall building which reflects the sound waves. If speed of sound in air be $320 \mathrm{~m} / \mathrm{sec}$, the frequency of siren heard by car driver is.

172958 A whistle of frequency $540 \mathrm{~Hz}$ rotates along a circle of radius $2 \mathrm{~m}$ an angular speed of $15 \mathrm{rad}$ $\mathrm{s}^{-1}$. The difference in maximum and minimum frequencies heard by a listener at some distance and at rest with respect to the centre of the circle is.
(Speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

172959 A train sounds its whistle as it approaches an observer standing at a point near the track. The observer measures a frequency of $216 \mathrm{~Hz}$ as the train approaches and a frequency of $\mathbf{1 8 4}$ $\mathrm{Hz}$ as the train leaves. What is the frequency of its whistle?