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A family ice show is held at an enclosed arena. The skaters perform to music with
level 80.0 dB. This is too loud for your baby, who yells at 75.0 dB. (a) What total
sound intensity engulfs you? (b) What is the combined sound level?
1 / 10
1
1.32 x 10-4 W/m2 , 81,2 dB
2
1.42 x 10-4 W/m2 , 80,2 dB
3
1.52 x 10-4 W/m2 , 81,2 dB
4
1.62 x 10-4 W/m2 , 83,2 dB
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A loudspeaker is placed between two observers who are 110 m apart, along the line
connecting them. If one observer records a sound level of 60.0 dB and the other
records a sound level of 80.0 dB, how far is the speaker from each observer?
2 / 10
1
R2 = 20 m and R1 = 90 m
2
R2 = 10 m and R1 = 100 m
3
R2 = 5 m and R1 = 105 m
4
R2 = 1 m and R1 = 109 m
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Two small speakers emit sound waves of different frequencies. Speaker A has an
output of 1.00 mW , and speaker B has an output of 1.50 mW . Determine the sound
level (in dB) at point C if (a) only speaker A emits sound, (b) only speaker B emits
sound, and (c) both speakers emit sound.
3 / 10
1
68 dB ; 67.8 dB ; 69.6 dB
2
65 dB ; 68.8 dB ; 69.6 dB
3
65 dB ; 67.8 dB ; 69.6 dB
4
65 dB ; 67.8 dB ; 70.6 dB
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A tuning fork vibrating at 512 Hz falls from rest and accelerates at 9.80 m/s2. How far
below the point of release is the tuning fork when waves of frequency 485 Hz reach
the release point? Take the speed of sound in air to be 340 m/s .
4 / 10
1
23.3 m
2
22.3 m
3
20.3 m
4
19.3 m
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A string with a mass of 8.00 g and a length of 5.00 m has one end attached to a wall;
the other end is draped over a pulley and attached to a hanging object with a mass
of 4.00 kg. If the string is plucked, what is the fundamental frequency of vibration?
5 / 10
1
15.7 Hz
2
17.7 Hz
3
18.7 Hz
4
16.7 Hz
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If two adjacent natural frequencies of an organ pipe are determined to be 550 Hz
and 650 Hz, calculate the fundamental frequency and length of this pipe. (Use v =340
m/s.)
6 / 10
1
60 Hz ; 1.7 m
2
50 Hz ; 1.7 m
3
50 Hz ; 1.8 m
4
60 Hz ; 2.7 m
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A student holds a tuning fork oscillating at 256 Hz. He walks toward a wall at a
constant speed of 1.33 m/s. (a) What beat frequency does he observe between the
tuning fork and its echo? (b) How fast must he walk away from the wall to observe a
beat frequency of 5.00 Hz?
7 / 10
1
3.99 Hz ; 4.38 m/s
2
2.99 Hz ; 3.38 m/s
3
1.99 Hz ; 3.38 m/s
4
0.99 Hz ; 3.48 m/s
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Light with wavelength 442 nm passes through a double-slit system that has a slit
separation d = 0.400 mm. Determine how far away a screen must be placed in order
that a dark fringe appear directly opposite both slits, with just one bright fringe
between them.
8 / 10
1
46.2 cm
2
50.2 cm
3
40.2 cm
4
36.2 cm
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White light is spread out into its spectral components by a diffraction grating. If the
grating has 2 000 grooves per centimeter, at what angle does red light of wavelength
640 nm appear in first order?
9 / 10
1
7.350
2
7.450
3
8.350
4
9.350
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Three polarizing disks whose planes are parallel are centered on a common axis. The
direction of the transmission axis in each case is shown in the figure below relative to the
common vertical direction. A plane-polarized beam of light with E0 parallel to the vertical
reference direction is incident from the left on the first disk with intensity Ii =10.0 W/m2.
Calculate the transmitted intensity If when (a) θ1=20.0°, θ2 =40.0°, and θ3 = 60.0° !
10 / 10
1
6.89 W/m2
2
7.89 W/m2
3
8.89 W/m2
4
9.89 W/m2
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