Posted by **jean** on Friday, April 1, 2011 at 9:10am.

A car traveling at 24.3 m/s honks its horn as it directly approaches the side of a large building. The horn produces a long sustained note of frequency f0 = 213 Hz. The sound is reflected off the building back to the car's driver. The sound wave from the original note and that reflected off the building combine to create a beat frequency. What is the beat frequency that the driver hears (which tells him that he had better hit the brakes!)? Assume the speed of sound in air is 342 m/s.

- physics -
**drwls**, Friday, April 1, 2011 at 9:24am
Calculate the Doppler-shifted frequency of the received echo, fr.

Let V be the car speed and a the speed of sound.

fr = fo*[(V+a)/(V-a)] = 1.153*fo = 246 Hz

Subtract fo from that for the beat frequency, 33 Hz

## Answer This Question

## Related Questions

- physics - A car traveling at 22.1 m/s honks its horn as it directly approaches ...
- physics - A car traveling at 22.1 m/s honks its horn as it directly approaches ...
- physics - 1)As a sound source moves away from a stationary observer, the number ...
- physics - 1)As a sound source moves away from a stationary observer, the number ...
- Physics!! - A car moving at 16.0 m/s, passes an observer while its horn is ...
- DrBob222 - A car moving at 16.0 m/s, passes an observer while its horn is ...
- Physics - A man driving a car toward a large vertical wal sounds his horn. The ...
- chemistry physics - A car is traveling toward you at 40.0 mi/h. The car horn ...
- Physics - A train sounds its horn as it approaches an intersection. The horn can...
- PHYSICS - A CAR IS TRAVELING TOWARDS YOU AT 70.0 MI/H. THE CAR HORN PRODUCES A ...

More Related Questions