Waves - Result Question 68
70. Two cars moving in opposite directions approach each other with speed of $22 m / s$ and $16.5 m / s$ respectively. The driver of the first car blows a horn having a frequency $400 Hz$. The frequency heard by the driver of the second car is [velocity of sound $340 m / s$ ] : [2017]
(a) $361 Hz$
(b) $411 Hz$
(c) $448 Hz$
(d) $350 Hz$
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Answer:
Correct Answer: 70. (c)
Solution:
- (c) As we known from Doppler’s Effect
$f _{\text{apprent }}=f_0[\frac{v+v_0}{v-v_s}]=400[\frac{340+16.5}{340-22}]$
$f _{\text{apprent }}=448 Hz$
$A \xrightarrow[f_0=400 Hz]{V_s=22 m / s} \stackrel{V_0=16.5 m / s}{\stackrel{ }{\circ}} B$
