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 12 Hz; if you are moving towards the 'clicker' at 15 m/sec what apparent frequency do you hear instead?
2.40 Hz
11.47 Hz
12.53 Hz
21.60 Hz
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Question 2
You are riding a bike away from a street musician at 7.5 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?
450 Hz
430 Hz
446 Hz
434 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 676 Hz, what is the actual frequency of the car horns.
600 Hz
608 Hz
761 Hz
752 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 15 crests every 10 seconds. Shortly afterwards you come to rest on the water and measure the waves to have an actual frequency of 7 every 10 seconds with a wave speed of 12.7 m/sec. How fast was your boat traveling before?
4.0 m/sec
39.9 m/sec
14.5 m/sec
11.1 m/sec
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Question 5
You are speeding away from a loud speaker. If the original frequency of 676 Hz is shifted to 638 Hz, what is your speed away from the speaker?
19.1 m/sec
20 m/sec
9 m/sec
32 m/sec
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Question 6
You are measuring the speed of a projectile using sonar. If a frequency of 338 Hz is reflected back at 330.5 Hz, what is the speed of the projectile?
45.3 m/sec
7.5 m/sec
7.7 m/sec
33.2 m/sec
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Question 7
In what direction was the projectile in
Question 6
moving relative to the sonar device?
cannot be determined
away from the sonar
towards the sonar
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William A. Hilburn
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