Concept Questions The table shows three situations in which...

Concept Questions The table shows three situations in which the Doppler effect may arise. The first two columns indicate the velocities of the sound source and the observer, where the length of each arrow is proportional to the speed. For each situation, fill in the empty columns by deciding whether the wavelength of the sound and the frequency heard by the observer increase, decrease, or remain the same compared to the case when there is no Doppler effect. Provide a reason for each answer. $$ \begin{array}{|l|c|c|c|c|} \hline & \begin{array}{c} \text { Velocity of Sound } \\ \text { Source (Toward the } \\ \text { Observer) } \end{array} & \begin{array}{c} \text { Velocity of } \\ \text { Observer (Toward } \\ \text { the Source) } \end{array} & \text { Wavelength } & \begin{array}{c} \text { Frequency Heard by } \\ \text { Observer } \end{array} \\ \hline \text { (a) } & 0 \mathrm{~m} / \mathrm{s} & 0 \mathrm{~m} / \mathrm{s} & & \\ \hline \text { (b) } & \rightarrow & 0 \mathrm{~m} / \mathrm{s} & & \\ \hline \text { (c) } & \rightarrow & \leftarrow & & \\ \hline \end{array} $$ Problem The siren on an ambulance is emitting a sound whose frequency is $2450 \mathrm{~Hz}$. The speed of sound is $343 \mathrm{~m} / \mathrm{s}$. (a) If the ambulance is stationary and you (the "observer") are sitting in a parked car, what is the wavelength of the sound and the frequency heard by you? (b) Suppose the ambulance is moving toward you at a speed of $26.8 \mathrm{~m} / \mathrm{s}$. Determine the wavelength of the sound and the frequency heard by you. (c) If the ambulance is moving toward you at a speed of $26.8 \mathrm{~m} / \mathrm{s}$ and you are moving toward it at a speed of $14.0 \mathrm{~m} / \mathrm{s}$, find the wavelength of the sound and the frequency that you hear. Be sure that your answers are consistent with your answers to the Concept Questions.

Concept Questions The table shows three situations in which the Doppler effect may arise. The first two columns indicate the velocities of the sound source and the observer, where the length of each arrow is proportional to the speed. For each situation, fill in the empty columns by deciding whether the wavelength of the sound and the frequency heard by the observer increase, decrease, or remain the same compared to the case when there is no Doppler effect. Provide a reason for each answer.
$$
\begin{array}{|l|c|c|c|c|}
\hline & \begin{array}{c}
\text { Velocity of Sound } \\
\text { Source (Toward the } \\
\text { Observer) }
\end{array} & \begin{array}{c}
\text { Velocity of } \\
\text { Observer (Toward } \\
\text { the Source) }
\end{array} & \text { Wavelength } & \begin{array}{c}
\text { Frequency Heard by } \\
\text { Observer }
\end{array} \\
\hline \text { (a) } & 0 \mathrm{~m} / \mathrm{s} & 0 \mathrm{~m} / \mathrm{s} & & \\
\hline \text { (b) } & \rightarrow & 0 \mathrm{~m} / \mathrm{s} & & \\
\hline \text { (c) } & \rightarrow & \leftarrow & & \\
\hline
\end{array}
$$
Problem The siren on an ambulance is emitting a sound whose frequency is $2450 \mathrm{~Hz}$. The speed of sound is $343 \mathrm{~m} / \mathrm{s}$. (a) If the ambulance is stationary and you (the "observer") are sitting in a parked car, what is the wavelength of the sound and the frequency heard by you? (b) Suppose the ambulance is moving toward you at a speed of $26.8 \mathrm{~m} / \mathrm{s}$. Determine the wavelength of the sound and the frequency heard by you.
(c) If the ambulance is moving toward you at a speed of $26.8 \mathrm{~m} / \mathrm{s}$ and you are moving toward it at a speed of $14.0 \mathrm{~m} / \mathrm{s}$, find the wavelength of the sound and the frequency that you hear. Be sure that your answers are consistent with your answers to the Concept Questions.

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