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 19 Hz; if you are moving towards the 'clicker' at 29 m/sec what apparent frequency do you hear instead?
31.45 Hz
17.38 Hz
20.62 Hz
6.55 Hz
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Question 2
You are riding a bike away from a street musician at 14.5 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?
421 Hz
459 Hz
451 Hz
429 Hz
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Question 3
You are in an ambulance driving towards an accident at 38 m/sec. You hear the horns of the cars in the accident sounding at a frequency of 360 Hz, what is the actual frequency of the car horns.
400 Hz
405 Hz
324 Hz
320 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 29 crests every 10 seconds. Shortly afterwards you come to rest on the water and measure the waves to have an actual frequency of 14 every 10 seconds with a wave speed of 12.7 m/sec. How fast was your boat traveling before?
39.0 m/sec
13.6 m/sec
4.1 m/sec
11.9 m/sec
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Question 5
You are speeding away from a loud speaker. If the original frequency of 360 Hz is shifted to 322 Hz, what is your speed away from the speaker?
40 m/sec
9 m/sec
30 m/sec
35.9 m/sec
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Question 6
You are measuring the speed of a projectile using sonar. If a frequency of 180 Hz is reflected back at 165.5 Hz, what is the speed of the projectile?
27.4 m/sec
29.8 m/sec
31.3 m/sec
23.4 m/sec
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Question 7
In what direction was the projectile in
Question 6
moving relative to the sonar device?
towards the sonar
away from the sonar
cannot be determined
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William A. Hilburn
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