NEET Solved Paper 2014 Question 22
Question: A speeding motorcyclist sees traffic jam ahead of him. He slows down to 36 km/h. He finds that traffic has eased and a car moving head of him at 18 km/h 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 [AIPMT 2014]
Options:
A) 1332 Hz
B) 1372 Hz
C) 1412 Hz
D) 1454 Hz
Show Answer
Answer:
Correct Answer: C
Solution:
$ \Rightarrow $ As both observer and source are moving, we can use the formula of apparent frequency as
$ f=f _0( \frac{v+v _0}{v+v _{s}} ) $ $ =1392[ \frac{343+10}{343+5} ] $ $ =1392[ \frac{353}{348} ]Hz $ $ =1412 $
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