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A speeding motorcyclist sees traffic jam ahead of him. He slows down to 36 km/hour. He finds that traffic has eased and a car moving ahead of him at 18 km/hour is honking at a frequency of 1392 Hz. If the speed of sound is 343 m/s, the frequency of the honk as heard by him will be:
A
1332 Hz
B
1372 Hz
C
1412 Hz
D
1464 Hz
Detailed Solution
$v_0 = 36$ km/h = 10 m/s (observer), $v_s = 18$ km/h = 5 m/s (source)
$n' = n\left[\frac{v + v_0}{v + v_s}\right] = 1392\left[\frac{343 + 10}{343 + 5}\right] = 1412$ Hz
$n' = n\left[\frac{v + v_0}{v + v_s}\right] = 1392\left[\frac{343 + 10}{343 + 5}\right] = 1412$ Hz