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SOUND
1. What is the period of a sound wave that has a
frequency of 2,500 Hz?
2. What is the frequency of a light wave that has a
period of 1.6 x 10 -15 sec?
3. What is the wavelength of light in problem #2?
(velocity of light = 3 x 108 m/s)
4. What is the wavelength of the sound wave in problem
#1?
5. The pendulum in a grandfather clock makes the floor
vibrate with a period of 0.5 seconds. What would
6. How often does a compression pass an observer who is
listening to a sound wave whose length of
7. A sound wave whose velocity in a particular medium is
600 m/s and has a wavelength of 300 cm.
8. Many species of bats are known to find their prey by
a kind of sonar using short bursts of ultra-sonic waves
(waves above the limit of human hearing). What is the wavelength of this wave if the
frequency
10. What is the shortest and longest wavelength sound
that can be heard by a human, if the frequency
11. What is the wavelength of waves broadcast by a TV
station whose frequency of transmission is
12. A tuning fork is vibrating with a frequency of 550
Hz simultaneously with another tuning fork. Beats
13. A violin string emits a sound having a frequency of
440 Hz.
(A) What is the
wavelength of the sound disturbance that passes through the air?
(B)
What is the period of this sound disturbance?
14. A tuning fork with a frequency of 600 Hz sends out
waves which travel at 1,080 ft/s. How many
15. When a sound wave is transferred from one medium to
another, its frequency does not change.
(A) water (V = 1,450 m/s)
(B) steel (V = 5,000 m/s)
(C) brass (V =3,500 m/s).
16. A source of sound sends out waves with a frequency
of 500 Hz that travel from air into water. Find
17. At what temperature would the velocity of sound in
air be 370 m/s if it is 331.5 m/s at 0o C?
18. A timer sets his watch by the report of a gun 100 m
away. What is the error recorded on his watch
19. A worker strikes the steel rails of a railroad
track. A person 1 km away hears two reports, one through
20. A workman strikes the rail of a railroad track with
a hammer. The sound thus produced reaches the
21. The vertical walls of a canyon are 8,800 m apart. A
man in the canyon fires a gun and hears the
22. One ship sends signals to a neighboring ship. The
sound travels by two paths, air and water. The
23. The limits of hearing of an older person are 40 Hz
and 8,500 Hz. Compute the minimum and
24. A submarine detects the presence of an enemy ship by
reflected sound waves (sonar). The echo
25. In mapping out the floor of the ocean, a sound wave
is reflected back to the surface in 0.8 seconds when
the velocity of sound in water is 1,450 m/s. What is the depth of the water?
26. A clap of thunder is heard 10 seconds after the
accompanying lightning flash. How far away is the
27. Sound waves pass from air into water in which the
velocity of sound is 1,450 m/S. The frequency of the
sound wave is 400 Hz and the air temperature is 0oC. What is the wavelength of
this sound in:
(A) air?
(B) water?
28. A ship lies between a horn buoy and a cliff. An
observer on a ship hears the horn buoy 2 seconds
(A) the cliff?
(B) the horn buoy?
29. If the ship in problem #28 were on the far side of
the buoy from the cliff and all other factors remain
(A) cliff?
(B) buoy?
30. Two railroad trains approach one another on parallel
tracks, each blowing its 500 Hz whistle. The velocity
of train “A” is 60 km/hr while “B” is 80 km/hr. An observer travels on
a highway that is parallel to the tracks with a
velocity of 10 km/hr and the air temperature is 20o C. As they approach
(A) train “A’s” engineer hear [(1); approach (2) recede]
(B) train “B’s” engineer hear [(1) approach; (2) recede]
(C) the observer in the car hear [train “A” approaching and receding and
train “B” approaching and receding].
31. An explosion is seen by an observer 2 seconds before
it is heard when the air temperature is 10oC.
32. Calculate the wavelength of the note emitted by a
string whose frequency of vibration is 512 Hz when
33. A man hunting ducks in the middle of a lake fires
his shotgun. Five seconds later he hears an echo
34. A gunner stationed 4,500 ft from a cliff fired his
gun and heard the echo from the cliff 8 seconds later.
(A) What was the velocity of sound at this time?
(B) What was the air temperature?
35. A timer at the track meet is standing at the finish
line for the 200 m race. He starts his stopwatch
(A) Will the timer’s watch be fast or slow? Explain.
(B) By what factor?
36. A man observes a flash of lightning and 6 seconds
later hears the thunder when the air temperature is
25oC. How far away was the lightning flash?
37. While working in the field, a farmer sets his pocket
watch by the sound of the 12:00 o’clock noon
(A) If the air temperature is 16oC, will his watch be fast or slow?
(B) By what factor?
38. A 12 inch air column produces its fundamental
resonance with a certain tuning fork when the air
39. A closed organ pipe is 8.75 ft in length.
(A) What fundamental frequency sound will this pipe produce?
(B) What possible wavelength sound(s) may this pipe produce?
40. A uniform flexible 10 m cord carries a wave which is
traveling at 18 m/s.
(A) What fundamental frequency wave could be produced in this cord?
(B) What is the wavelength of this disturbance?
41. A tuning fork makes 1,000 vib/s in air at 20oC.
What would be its wavelength in:
(A) meters?
(B) ft?
42. A vibrator submerged in water produces a 500 Hz
sound. The velocity of sound in this water is
(A) What is the wavelength of this sound wave?
(B) If the wave were to have the same frequency in air, what would be its
wavelength in air?
43. The limits of hearing of a particular person are 32
Hz and 1,600 Hz. When the air temperature is
(A) longest wave this person could hear?
(B) What is the shortest wave this person could hear?
44. Two hands are clapped together some distance in
front of a flat cliff face. The echo returns in
45. The thunder clap of a storm is heard 10 seconds
after the accompanying lightning flash when the
46. A
factory whistle has a frequency of 600 Hz. An observer approaching the whistle at a
velocity of
(A) approaches?
(B) recedes?
47. A man hammers on a steel railroad rail. You hear the
sound at your location first thru the rail, then through the air 5 seconds
later. The air
temperature is 45oC and the velocity of sound in the rail is
48. A rifle is fired in a canyon 11,650 m wide with
parallel walls. The echo is heard from the far wall
(A)
the near wall?
(B)
the far wall?
49. What is the wavelength in meters of the sound
produced by a 320 Hz tuning fork when the air
50. What is the frequency of a tuning fork which
resonates with a 25 cm long open tube that is 2 cm
51. How many beats will be heard when a 288 Hz string is
simultaneously plucked with a 320 Hz
52. The echo of a ship’s fog horn is reflected from
an iceberg and is heard 5 seconds after being sounded.
If the air temperature is -35oC, How far away is the iceberg?
53. A rifle is fired in a valley whose parallel walls
are 6,800 m apart. An echo is heard from the near wall
5 seconds before the echo from the far wall when the air temperature is 35oC.
How far is the rifle from the:
(A)
near wall?
(B)
far wall?
54. A worker sets his watch by the sound of a clock in a
neighboring town 3 km away on a day when
55. A field judge fires a starters pistol and hears the
echo from the bleachers 0.75 sec later when the
56. In a laboratory experiment with resonance tubes, we
hear resonance produced with a particular
(A) What wavelength sound is heard?
(B) What is the frequency of the tuning fork being used?
57. In an experiment with two closed resonance tubes, we
hear the first resonant sound produced with a
(A)
What is the frequency of each tuning fork required for each tube [tube “A” and
tube “B”]?
(B)
What will be the number of beats produced from these resonant sounds?
58. The vertical walls of a 27,750 m wide canyon are
parallel. A man inside the canyon fires a gun and
(A)
near wall?
(B)
far wall?
59. An open pipe 26 cm long and 1.75 cm in diameter is
in an environment of -12oF.
(A) What are the frequency sounds that are produced for the first three points of
resonance?
(B) What will be the wavelengths of these sounds respectively?
(C) Diagram each of these sounds?
60. A carpenter is putting a new roof on a house and
from where you are watching, you see the hammer
61. A man in a canyon fires a gun and hears the echo
from the far wall 5 seconds after he hears the echo
(A) near wall?
(B) far wall?
62. You are in the grandstands at the Indianapolis 500
auto race when you observe a car traveling at 180
mi/hr and is emitting a 385 Hz sound. What frequency sound will you hear as he: (A)
approaches
"Physics for Scientists and Engineers" text (Prentice-Hall, Inc., Publisher): Chapter 16 - Sound. Click on "Practice Questions" in the left window. Answer problems #10, 11, 12, 16, 17, 18, 19, 20, 22, 24, 25. Also, click on "Practice Problems" #1, 2, 5, 6, 7, 8.
Physics 1070, University of Guelph, Canada. Study Guide 2 - Acoustics. Self Test 3 : Each problem is linked to its solution. Solve the following problems: #1 (fundamental frequency for an open and closed pipe), #2 (next harmonic for pipes in problem 1), #3 (given numeric values for variables, solve for each pipe's fundamental frequency), #4 (an open pipe problem). Self Test 4 : Solve the following problems: #1 (beats and possible frequencies), #2 and #3 (best hearing threshold - solve for basic knowledge). Self Test 5 : This set involves the intensity, power, and energy associated with sound. This section may or may not be developed in class this year.
Multiple Choice
1. Sound is caused by objects that:
(A)
reflect
(C) transmit
(B) vibrate (D) absorb
2. Sound will not travel through:
(A)
air
(C) a vacuum
(B) water (D) the Earth
3. The pitch of a sound is determined by its:
(A)
vibration rate
(D) amplitude
(B) speed (E) loudness
(C)
reflection;
4. A closed organ pipe will resonate with:
(A) a node at each end
(B) a node at the closed end and a loop at the open end
(C) a node at the open end and a loop at the closed end
(D) a loop at both ends
5. Waves in which the particles of the medium vibrate
parallel to the direction of wave motion is called
(A)
light wave
(C) transverse wave
(B) spiral wave ( D) longitudinal wave
6. Sounds are BEST transmitted in which of
the following materials states if their temperatures are the
(A)
vapors
(C) gases
(B) solids (D) liquids
7. If the energy of a sound wave is decreased:
(A)
the frequency increases
(C) the pitch decreases
(B) the amplitude decreases (D) the amplitude increases
8. The period of vibration is:
(A)
the reciprocal of the frequency
(C) the reciprocal of the amplitude
(B) the number of vibrations per second (D) the reciprocal of the intensity
9. When a 45 rpm record is played at 78 rpm:
(A)
the pitch is lowered
(C) diffraction is produced
(B) interference is produced (D) the pitch is raised
10. Two tuning forks that are vibrating simultaneously
produce 6 beats/sec. If the frequency of one of
(A) 266 Hz
(C) 258 Hz
(B) 262 Hz (D) 254 Hz
11. The three properties of a wave that are related to
each other in a definite way are:
(A) wavelength, velocity and energy (C) wavelength, energy and frequency
(B) wavelength, velocity and frequency (D) energy, velocity and frequency
12. The Doppler Effect occurs when motion of the source
or an observer causes:
(A) waves to change in observed frequency
(B) waves to change their direction of travel
(C) electromagnetic waves to be slowed
(D) wave energy to be converted to some other kind of energy
13. The speed of sound is affected by all of the
following EXCEPT :
(A) pressure
(C) volume
(B) temperature (D) density
14. When a sound is transmitted from one medium to
another, the frequency:
(A) is always the same
(B) is sometimes the same
(C) is never the same
15. One important characteristic of standing waves is:
(A) their wavelength must be some whole number of their length of travel
(B) they all move at the same velocity
(C) is never the same
Matching
1. vibration
A. Uniform frequency pattern
2. echo
B. frequencies greater than 20K Hz
3. pitch
C. maximum deflection of the medium particles
4. noise
D. uneven frequency patterns
5. musical sound
E. multiple reflections
6. ultrasonic
F. reflected waves
7. loudness
G. forced vibrations caused by a source of sound
8. resonance
H. will not transmit sound
9. vacuum
I. moving object causing sound
J.
determined by frequency
K. determined by energy put into the
sound