Practice Problems
Doppler Effect
Directions:
On this worksheet, you may assume that the speed of sound in air is 340 m/sec unless otherwise stated.
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Question 1
A 'clicker' is sounding at 15 Hz; if you are moving towards the 'clicker' at 19 m/sec what apparent frequency do you hear instead?
3.16 Hz
26.84 Hz
14.16 Hz
15.84 Hz
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Question 2
You are riding a bike away from a street musician at 9.5 m/sec; when the trumpet player hits an 'A'. You know that the frequency of an 'A' should be 440 Hz, what apparent frequency do you hear instead?
428 Hz
452 Hz
447 Hz
433 Hz
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Question 3
You are in an ambulance driving towards an accident at 43 m/sec. You hear the horns of the cars in the accident sounding at a frequency of 471 Hz, what is the actual frequency of the car horns.
418 Hz
539 Hz
531 Hz
411 Hz
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Question 4
You are riding in a boat into oncoming waves and measure the frequency of the waves to be 19 crests every 10 seconds. Shortly afterwards you come to rest on the water and measure the waves to have an actual frequency of 10 every 10 seconds with a wave speed of 14.3 m/sec. How fast was your boat traveling before?
41.5 m/sec
12.9 m/sec
4.9 m/sec
15.9 m/sec
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Question 5
You are speeding away from a loud speaker. If the original frequency of 471 Hz is shifted to 428 Hz, what is your speed away from the speaker?
34 m/sec
31.0 m/sec
31 m/sec
8 m/sec
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Question 6
You are measuring the speed of a projectile using sonar. If a frequency of 235.5 Hz is reflected back at 226 Hz, what is the speed of the projectile?
13.7 m/sec
14.3 m/sec
32.6 m/sec
35.8 m/sec
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Question 7
In what direction was the projectile in
Question 6
moving relative to the sonar device?
away from the sonar
cannot be determined
towards the sonar
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William A. Hilburn
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