a)
let I is the intensity of the sound 1t 1 km.
we know, sound intensity level
beta = 10*log(I/Io)
40 = 10*log(I/10^-12)
4 = log(I/10^-12)
10^4 = I/10^-12
I = 10^(-12 + 4)
I = 10^-8 W/m^2
let I' is the intensity when loudness is 86 dB
simillarly,
I' = 10^(-12 + 8.6)
= 3.98*10^-4 W/m^2
let r = 1 km and r' is the new distance.
we know, Intensity is inversely proportional to r^2
I/I' = (r'/r)^2
r' = sqrt(I/I')*r
= sqrt(10^-8/(3.98*10^-4))*1*10^3
= 5.01 m <<<<<<<--------------Answer
b) apparent frequency of the police car, f' = f*(v_sound + v)/v_sound
= 800*(343 + 10)/343
= 823.3 Hz <<<<<<<--------------Answer
c) frequency heard = f' - f
= 823.3 - 800
= 23.3 Hz <<<<<<<--------------Answer
14. You are driving an ambulance through traffic at 10 m/s to the scene of a...
You are driving down the road at 15.6 m/s (35 mph) when an ambulance passes you with its siren blaring. The ambulance siren produces a frequency of 700 Hz. As the ambulance approaches you from behind, you hear a frequency of 730 Hz . The speed of sound in air is 344 m/s. What is the speed of the ambulance? The positive direction points from your car (listener) toward the ambulance (source). Express your answer in meters per second.
You are driving at a velocity of 95 MPH (42.5 m/s) when you hear a police siren behind you. From your previous run-ins with the law, you know that at a particular point in the sound, the police sirens on the police cars in your town emit a frequency of 751.255 Hz. You hear the sound at a frequency of 752.551 Hz. How fast the the police car going (in m/s)? (Assume that the speed of sound is 343 m/s.)
you are driving along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind at constant speed and you perceive the frequency as 1310 Hz. you are relieved that he is in pursuit of a different driver when he continues past you, but now you perceive the frequency as 1240 hz. what is the frequency of the siren in the police car? the speed of sound in air is 343 m/s
2. (19 points) You are driving along a highway when you hear the siren of a police car driving at approaching you from behind, and you perceive the frequency as 1320 Hz. You are relieved that he is in pursuit of a speeding Porsche 911car when he continues past you, but now you perceive the frequency as 1265 Hz. (The speed of sound in the air is 344 m/s.) m/ a) What is the frequency of the siren in the...
You are driving down the highway at 14.9 m/s when you approach an automobile accident on the side of the road. To keep traffic away from it, a stationary police car has its siren going; to the police, the siren has a frequency of 1100 Hz. If the speed of sound in air is 332 m/s, what frequency (in Hz) will be heard by you in your car? If the relative motion in the previous question was reversed (i.e. if...
please help. thank you lots You are driving down the road at 15.6 m/s (35 mph) when an ambulance passes you with its siren blaring. The ambulance siren produces a frequency of 700 Hz. As the ambulance approaches you from behind, you hear a frequency of 740 Hz. The speed of sound in air is 344 m/s. Part A What is the speed of the ambulance? The positive direction points from your car istener) toward the ambulance (source) Express your...