Wave Mechanics Question 1008
Question: The driver of a car travelling with speed 30 metres per second towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 metres per second, the frequency of the reflected sound as heard by the driver is
[MP PMT 1996]
Options:
A) 720 Hz
B) 555.5 Hz
C) 550 Hz
D) 500 Hz
Show Answer
Answer:
Correct Answer: A
Solution:
From the figure, it is clear that Frequency of reflected sound heard by the driver. $ n’=n,[ \frac{v-(-v _{o})}{v-v _{s}} ]=n,[ \frac{v+v _{o}}{v-v _{s}} ]=n,[ \frac{v+v _{car}}{v-v _{car}} ] $
$ =600,[ \frac{330+30}{330-30} ]=720,Hz. $
BETA
