Zzztayloe, Rex – Homework 13 – Heinz – 81204 – Nov 04, 2004
1
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The due time is Central
time.
001
(part 1 of 1) 10 points
Find the speed of sound in tungsten, which
has a bulk modulus of approximately 2
×
10
11
N
/
m
2
and a density of 19250 kg
/
m
3
.
Correct answer: 3
.
22329 km
/
s.
Explanation:
Given
:
B
= 2
×
10
11
N
/
m
2
and
ρ
= 19250 kg
/
m
3
.
The speed of sound caused by tungsten’s com
pressibility is
v
=
s
B
ρ
=
s
2
×
10
11
N
/
m
2
19250 kg
/
m
3
1 km
1000 m
¶
=
3
.
22329 km
/
s
.
002
(part 1 of 1) 10 points
Some studies suggest that the upper fre
quency limit of hearing is determined by the
diameter of the eardrum.
The wavelength
of the sound wave and the diameter of the
eardrum are approximately equal at this up
per limit.
If this is precisely true, what is the diameter
of the eardrum of a person capable of hearing
21393 Hz?
(Assume a body temperature of
36
.
2
◦
C.) The speed of sound in air at 0
◦
C is
331 m
/
s.
Correct answer: 1
.
64663 cm.
Explanation:
Given :
f
= 21393 Hz
.
v
0
= 331 m
/
s
,
and
T
= 36
.
2
◦
C = 309
.
2 K
.
The speed of sound in air is
v
=
fλ
=
v
0
r
T
273
K
λ
=
v
0
f
r
T
273
K
=
331 m
/
s
21393 Hz
r
309
.
2 K
273 K
100 cm
m
¶
=
1
.
64663 cm
.
003
(part 1 of 3) 4 points
An outside loudspeaker (considered a small
source) emits sound waves with a power out
put of 79 W.
Find the intensity 11
.
9 m from the source.
Correct answer: 0
.
0443939 W
/
m
2
.
Explanation:
Given :
P
= 79 W
and
r
= 11
.
9 m
.
The wave intensity is
I
=
P
4
π r
2
=
79 W
4
π
(11
.
9 m)
2
=
0
.
0443939 W
/
m
2
.
004
(part 2 of 3) 3 points
Find the intensity level in decibels at this
distance.
Correct answer: 106
.
473 dB.
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 Fall '09
 WOODAHL
 Physics, Work, Correct Answer, Zzztayloe

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