4.- In a rescue vehicle is an injured person who suffered an accident. The Ambul

Question

4.- In a rescue vehicle is an injured person who suffered an accident. The Ambulance is away from the construction where minutes before picked up the person. Speed With which the vehicle is away is constant at 40 mph. The siren emits a frequency of 400 Hz. After the siren is turned off, the injured person can hear the sound reflected on the wall. The construction for a few seconds.

A)What is the speed of sound in the air if the Ambient temperature is 23 ° C,?

B). What is the frequency of the siren sound of the Ambulance reflected on the wall of the building and heard the injured person?

C) What is The separation of sound waves after reflection, behind the ambulance?

Explanation / Answer

A) taking the relation between temperature and sound we get sound speed at T as

V=331+.6/C*T=331+.6/3*10^8* 296=331.000001m/s[T=23+273=296K]

B) the construction site is stationarybut ambulence is moving reflector then we can use Doppler formula to get the resultant frequency

siren frequency for ambulance= f'=(C-vs/C+vs)*f0=(3*10^8-17.88/3*10^8+17.88)*400=399hz

C) seperation of sound wave after reflection = speed/frequency= 17.88/399=.04481m

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