prac02 - The Physics of Light & Sound PRACTICE PROBLEMS...

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Unformatted text preview: The Physics of Light & Sound PRACTICE PROBLEMS GENERAL SCIENCE 121 SUMMER 2011 1. A pendulum on the Earth’s surface has a bob of length 0.2 m. What is the natural frequency in Hz Sean T 11 of this system? ANSWER: 1.11 Scully - GSCI121_3_4_SP10 Hz Homework #4 2. What length of pendulum is required to produce a period of 2 seconds? ANSWER: 1 m 4 Due date: Wed Feb 23:00:00 2010 3. What is the amplitude of the wave below:24 ANSWER: 1.5 m. 3 4 2 position (m) 3 Position (m) 2 1 1 0 −1 0 −2 −1 −3 −2 −4 0 −3 4 6 8 10 time (s) What −4 −4 What 2 is the −2 amplitude 0 Time (s) of 4. What is its period? ANSWER 6 seconds Tries 0/10 Answer • 1.5 for Part: 5. What is its frequency? ANSWER: 0.17[1.425 Hz 0 1.575] this 2 is the period of this wave (in seconds)? 4 Tries 0/10 wave (in meters)? Answer for Part: 0 • 6.0 [5.7 6.3] Water waves are observed to pass under a bridge at a rate of one complete wave every 3 s. What is the frequency (in hz) of these waves? 6. If this is a sound wave with c = Two instruments play a note is the same time. One produces ANSWER: 1986 m 331 m/s, what at its wavelength? Tries 0/10 a wave that has a frequency of 236 Hz and the other produces Answer • 0.333333333333333 a wave of 228 Hz. What is the frequency of the resulting beats for Part: 7. Two instruments play a note at(inthe same time. One produces a wave that has a frequency of 236 [0.316666666666666 Hz)? 0 0.35] Tries 0/10 of 228 Hz. What is the frequency of the0 resulting beats (in Hz and the other produces a wave Sig - 15 Answer •8 A vibrating tuning fork produces waves with a waveHz)? ANSWER: 8 Hz for Part: [7.6 length of 9 m and a frequency of 10 Hz. How fast do 0 8.4] these waves travel away from the tuning fork (in m/s)? 8. What frequency does your ear hear? ANSWER: 232 Hz Sig 0 - 15 Tries 0/10 9. Water waves are observed to pass under a bridge at a rate of oneAnswer complete wave every 3 s. What • 90 is the frequency (in Hz) of these waves? ANSWER: 0.33 Hz for Part: [85.5 0 94.5] Sig 0 - 15 10. A vibrating tuning fork produces waves with a wavelength of 9 m and a frequency of 10 Hz. How fast do these waves travel away from the tuning fork (in m/s)? ANSWER: 90 m/s 11. You are in the Grand Canyon. You yell out "HELLO!" 4 seconds later you hear your echo. How far away is the canyon wall (in meters) if the speed of sound through air is approximately 340 m/s? ANSWER: 680 m 12. A wave is observed to have a period of 8 seconds. What is the frequency of this wave (in Hz)? ANSWER: 0.125 Hz 13. A transverse wave is transporting energy from east to west. The particles of the medium will move: A) easterly B) Both northward and southward C) Both eastward and westward D) northerly Summer 2011 1 Practice Problems 14. A wave has a frequency of 256 Hz and a wavelength of λ = 1.1 m. What is the wave speed (in m/ s)? ANSWER: 282 m/s 15. A horn is known to emit a sound of 356 Hz when stationary. If the speed of sound is 340 m/s, how fast (away or towards) is the horn moving if the frequency heard is measured to be 400 Hz? ANSWER: 42 m/s towards the observer 16. A trumpet produces a pitch of 440 Hz. The trumpet is now set in motion away from the listener at a speed of 30 m/s. If the speed of sound is 340 m/s, what frequency would be heard by a stationary observer? ANSWER: 401 Hz 17. The temperature in Harrisonburg is 10 C. What is the speed of sound through air (in m/s)? ANSWER: 331.6 m/s 18. Which of the following are units of sound intensity? A) dB (decibels) B) kg m/s/s C) W/m (Watts per meter) D) W (Watts) 19. With one violin playing the sound level at a certain place is measured to be 50 dB. If instead 10 violins are play- ing equally as loudly, what will be the sound level (dB)? ANSWER: 60 dB 20. The background noise in a room is measured to be 63 dB. How many dB is 1000 times louder? ANSWER: 93 dB 21. A sound source produces a sound measured to be 66 dB at some distance. Suppose now I am twice as far away. What will my sound meter register? ANSWER: 63 dB 22. A triangle makes a sound of intensity 82 dB. How loud are two triangles? ANSWER: 85 dB 23. The part of the ear responsible for converting mechanical pressure into nerve impulses is: A) The Pinna B) The Stapes C) The Cochlea D) The Ear Drum 24. What is the log of 12589? ANSWER: 4.1 25. The human ear can hear frequencies from 20 hz up to 20,000 hz. What is the wavelength (in m) of the highest frequency a human can hear in air if the temperature is 10 C? ANSWER: 0.017 m Summer 2011 2 Practice Problems ...
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This note was uploaded on 06/02/2011 for the course GSCI 121 taught by Professor Niculescu,m during the Spring '08 term at James Madison University.

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