A detector is released from rest over a source of sound of freque… - Vidyadip

MCQ

A detector is released from rest over a source of sound of frequency $f = 10^3 \,\,Hz$. The frequency observed by the detector at time $t$ is plotted in the graph. The speed of sound in air is $(g = 10 \,\,m/s^2)$ ... $m/s$

A
$330$
B
$350$
✓
$300$
D
$310$

✓

Answer

Correct option: C.

$300$

c
$f=f_{o}\left(\frac{\nu+\nu_{o}}{\nu}\right)$

$=10^{3}\left(1+\frac{10 t}{\nu}\right)\left(\text { as } \nu_{o}=g t\right)$

Hence, $f$ versus $t$ graph is straight line of slope $\frac{10^{4}}{\nu}$

$\therefore \frac{10^{4}}{\nu}=$ slope $=\frac{100}{3}$

$\therefore \nu=300 \mathrm{m} / \mathrm{s}$

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