A source and a detector move away from each other in absence of w… - Vidyadip

MCQ

A source and a detector move away from each other in absence of wind with a speed of $20\, {m} / {s}$ with respect to the ground. If the detector detects a frequency of $1800\, {Hz}$ of the sound coming from the source, then the original frequency of source considering speed of sound in air $340\, {m} / {s}$ will be ${Hz}$

A
$1050$
B
$750$
✓
$2025$
D
$2250$

✓

Answer

Correct option: C.

$2025$

c
${V}_{{S}}=20 {m} / {s} \quad {V}_{{O}}=20 {m} / {s}$

${f}^{\prime}={f}\left(\frac{{V}-{V}_{0}}{{V}+{V}_{{s}}}\right)$

$1800={f}\left(\frac{340-20}{340+20}\right)$

${f}=2025 {Hz}$

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