172944 An obstacle is moving towards the source with velocity ' $V$ '. The sound is reflected from the obstacle. If ' $C$ ' is the speed of sound and ' $\lambda$ ' is the wavelength, then the wavelength of the reflected wave $\left(\lambda_{r}\right)$ is

172945 A railway engine whistling at a constant frequency moves with a constant speed. It goes past a stationary observer beside the railway track. Which of the following graphs best represent the variation of frequency of the sound (n) heard by the observer with the time (t)?

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172947 An engine sounding a whistle of frequency 2000 $\mathrm{Hz}$ is receding from the stationary observer at $72 \mathrm{~km} / \mathrm{h}$. What is the apparent frequency of the observer? The velocity of sound in air is 340 $\mathbf{m} / \mathbf{s}$.

172948 Two trucks heading in opposite directions each with speed $0.1 \mathrm{u}$, approach each other. The speed of the sound is $u$. The driver of first truck sounds his horn of frequency $495 \mathrm{~Hz}$. Let $v_{1}$ and $v_{2}$ are the frequencies heard by the driver of second truck, when the trucks approach each other and when the trucks have passed each other. The magnitude of $v_{1}-v_{2}$ is

172949 A bus moving with an uniform speed of 72 $\mathrm{km} / \mathrm{h}$ towards a building blows a horn of frequency $1.7 \mathrm{kHz}$. If speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$, what will be the frequency of echo heard by bus driver?

172944 An obstacle is moving towards the source with velocity ' $V$ '. The sound is reflected from the obstacle. If ' $C$ ' is the speed of sound and ' $\lambda$ ' is the wavelength, then the wavelength of the reflected wave $\left(\lambda_{r}\right)$ is

172945 A railway engine whistling at a constant frequency moves with a constant speed. It goes past a stationary observer beside the railway track. Which of the following graphs best represent the variation of frequency of the sound (n) heard by the observer with the time (t)?

1

2

3

4

172947 An engine sounding a whistle of frequency 2000 $\mathrm{Hz}$ is receding from the stationary observer at $72 \mathrm{~km} / \mathrm{h}$. What is the apparent frequency of the observer? The velocity of sound in air is 340 $\mathbf{m} / \mathbf{s}$.

172948 Two trucks heading in opposite directions each with speed $0.1 \mathrm{u}$, approach each other. The speed of the sound is $u$. The driver of first truck sounds his horn of frequency $495 \mathrm{~Hz}$. Let $v_{1}$ and $v_{2}$ are the frequencies heard by the driver of second truck, when the trucks approach each other and when the trucks have passed each other. The magnitude of $v_{1}-v_{2}$ is

172949 A bus moving with an uniform speed of 72 $\mathrm{km} / \mathrm{h}$ towards a building blows a horn of frequency $1.7 \mathrm{kHz}$. If speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$, what will be the frequency of echo heard by bus driver?

172944 An obstacle is moving towards the source with velocity ' $V$ '. The sound is reflected from the obstacle. If ' $C$ ' is the speed of sound and ' $\lambda$ ' is the wavelength, then the wavelength of the reflected wave $\left(\lambda_{r}\right)$ is

172945 A railway engine whistling at a constant frequency moves with a constant speed. It goes past a stationary observer beside the railway track. Which of the following graphs best represent the variation of frequency of the sound (n) heard by the observer with the time (t)?

1

2

3

4

172947 An engine sounding a whistle of frequency 2000 $\mathrm{Hz}$ is receding from the stationary observer at $72 \mathrm{~km} / \mathrm{h}$. What is the apparent frequency of the observer? The velocity of sound in air is 340 $\mathbf{m} / \mathbf{s}$.

172948 Two trucks heading in opposite directions each with speed $0.1 \mathrm{u}$, approach each other. The speed of the sound is $u$. The driver of first truck sounds his horn of frequency $495 \mathrm{~Hz}$. Let $v_{1}$ and $v_{2}$ are the frequencies heard by the driver of second truck, when the trucks approach each other and when the trucks have passed each other. The magnitude of $v_{1}-v_{2}$ is

172949 A bus moving with an uniform speed of 72 $\mathrm{km} / \mathrm{h}$ towards a building blows a horn of frequency $1.7 \mathrm{kHz}$. If speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$, what will be the frequency of echo heard by bus driver?

172944 An obstacle is moving towards the source with velocity ' $V$ '. The sound is reflected from the obstacle. If ' $C$ ' is the speed of sound and ' $\lambda$ ' is the wavelength, then the wavelength of the reflected wave $\left(\lambda_{r}\right)$ is

172945 A railway engine whistling at a constant frequency moves with a constant speed. It goes past a stationary observer beside the railway track. Which of the following graphs best represent the variation of frequency of the sound (n) heard by the observer with the time (t)?

1

2

3

4

172947 An engine sounding a whistle of frequency 2000 $\mathrm{Hz}$ is receding from the stationary observer at $72 \mathrm{~km} / \mathrm{h}$. What is the apparent frequency of the observer? The velocity of sound in air is 340 $\mathbf{m} / \mathbf{s}$.

172948 Two trucks heading in opposite directions each with speed $0.1 \mathrm{u}$, approach each other. The speed of the sound is $u$. The driver of first truck sounds his horn of frequency $495 \mathrm{~Hz}$. Let $v_{1}$ and $v_{2}$ are the frequencies heard by the driver of second truck, when the trucks approach each other and when the trucks have passed each other. The magnitude of $v_{1}-v_{2}$ is

172949 A bus moving with an uniform speed of 72 $\mathrm{km} / \mathrm{h}$ towards a building blows a horn of frequency $1.7 \mathrm{kHz}$. If speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$, what will be the frequency of echo heard by bus driver?

172944 An obstacle is moving towards the source with velocity ' $V$ '. The sound is reflected from the obstacle. If ' $C$ ' is the speed of sound and ' $\lambda$ ' is the wavelength, then the wavelength of the reflected wave $\left(\lambda_{r}\right)$ is

172945 A railway engine whistling at a constant frequency moves with a constant speed. It goes past a stationary observer beside the railway track. Which of the following graphs best represent the variation of frequency of the sound (n) heard by the observer with the time (t)?

1

2

3

4

172947 An engine sounding a whistle of frequency 2000 $\mathrm{Hz}$ is receding from the stationary observer at $72 \mathrm{~km} / \mathrm{h}$. What is the apparent frequency of the observer? The velocity of sound in air is 340 $\mathbf{m} / \mathbf{s}$.

172948 Two trucks heading in opposite directions each with speed $0.1 \mathrm{u}$, approach each other. The speed of the sound is $u$. The driver of first truck sounds his horn of frequency $495 \mathrm{~Hz}$. Let $v_{1}$ and $v_{2}$ are the frequencies heard by the driver of second truck, when the trucks approach each other and when the trucks have passed each other. The magnitude of $v_{1}-v_{2}$ is

172949 A bus moving with an uniform speed of 72 $\mathrm{km} / \mathrm{h}$ towards a building blows a horn of frequency $1.7 \mathrm{kHz}$. If speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$, what will be the frequency of echo heard by bus driver?