Question 506: Waves

Question

The driver of a car travelling with speed 30 m/s towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 m/s, the frequency of reflected sound as heard by driver is

Accepted Answer

Car is the source and the hill is observer. Frequency heard at the hill, $${\upsilon _1}$$
$$ 	herefore {\upsilon _1} = {{\upsilon  	imes v} \over {\left( {v - V} ight)}} = {{600 	imes 330} \over {330 - 30}}$$
Now for reflection, the hill is the source and the driver the observer.
$$ 	herefore $$ $${\upsilon _2} = {\upsilon _1} 	imes {{\left( {330 + 30} ight)} \over {330}}$$
$$ \Rightarrow {\upsilon _2} = {{600 	imes 330} \over {300}} 	imes {{360} \over {330}} \Rightarrow {\upsilon _2} = 720$$ Hz.

Answer

555.5 Hz

Answer

720 Hz

Answer

500 Hz

Answer

550 Hz

Waves

The driver of a car travelling with speed 30 m/s towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 m/s, the frequency of reflected sound as heard by driver is

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