wave_mechanics dopplers_effect Question 10
Question: A person feels 2.5% difference of frequency of a motor-car horn. If the motor-car is moving to the person and the velocity of sound is 320 m/sec, then the velocity of car will be
[CPMT 1981; MP PET 1989]
Options:
A) 8 m/s (approx.)
B) 800 m/s
C) 7 m/s
D) 6 m/s (approx.)
Show Answer
Answer:
Correct Answer: A
Solution:
By Doppler’s formula $ n’=\frac{nv}{(v-v _{S})} $ Since, source is moving towards the listener so $ n’>n $ .
If n = 100 then n' = 102.5
Therefore $ 102.5=\frac{100\times 320}{(320-v _{S})} $
Therefore $ v _{s}=8 $
$ m/\sec $
BETA
