Question:
Consider a vehicle emitting sound wave of frequency $700$ Hz moving towards an observer at a speed $22$ m/s. Assuming the observer as well as the medium to be at rest and velocity of sound in the medium to be $330$ m/s, the frequency of sound as measured by the observer is
Consider a vehicle emitting sound wave of frequency $700$ Hz moving towards an observer at a speed $22$ m/s. Assuming the observer as well as the medium to be at rest and velocity of sound in the medium to be $330$ m/s, the frequency of sound as measured by the observer is
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When source moves towards observer, frequency increases: use $v - v_s$ in denominator.
Updated On: May 1, 2026
- $\frac{2525}{4}$ Hz
- $\frac{1960}{3}$ Hz
- $\frac{2240}{3}$ Hz
- $750$ Hz
- $\frac{5625}{7}$ Hz
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The Correct Option is C
Solution and Explanation
Concept:
For source moving towards observer: \[ f' = f \cdot \frac{v}{v - v_s} \]
Step 1: Substitute values.
\[ f = 700,\quad v = 330,\quad v_s = 22 \] \[ f' = 700 \cdot \frac{330}{330 - 22} = 700 \cdot \frac{330}{308} \]
Step 2: Simplify.
\[ = 700 \cdot \frac{165}{154} = \frac{700 \times 165}{154} \] \[ = \frac{2240}{3} \text{ Hz} \]
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