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 17 Hz; if you are moving towards the 'clicker' at 21 m/sec what apparent frequency do you hear instead?
15.95 Hz
30.76 Hz
18.05 Hz
3.24 Hz
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Question 2
You are riding a bike away from a street musician at 10.5 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?
426 Hz
454 Hz
432 Hz
448 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 338 Hz, what is the actual frequency of the car horns.
381 Hz
295 Hz
300 Hz
387 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 21 crests every 10 seconds. Shortly afterwards you come to rest on the water and measure the waves to have an actual frequency of 12 every 10 seconds with a wave speed of 14.3 m/sec. How fast was your boat traveling before?
10.7 m/sec
39.3 m/sec
5.2 m/sec
19.1 m/sec
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Question 5
You are speeding away from a loud speaker. If the original frequency of 338 Hz is shifted to 295 Hz, what is your speed away from the speaker?
8 m/sec
50 m/sec
30 m/sec
43.3 m/sec
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Question 6
You are measuring the speed of a projectile using sonar. If a frequency of 169 Hz is reflected back at 158.5 Hz, what is the speed of the projectile?
21.1 m/sec
32.4 m/sec
22.5 m/sec
31.9 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
cannot be determined
away from the sonar
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