This preview shows pages 1–3. Sign up to view the full content.
HOMEWORK CH 14
4,8,12,16,20,24,29,33,35,51,53
14.4
The speed of sound in seawater at 25°C is
1 530 m s
. Therefore, the time for the sound to reach the sea
floor and return is
2
2(150 m)
0.196 s
1530 m/s
d
t
v
14.8
At a temperature of
T
= 10.0°C = 283 K, the speed of sound in air is
283 K
331 m s
331 m s
337 m s
273 K
273 K
T
v
The elapsed time between when the stone was released and when the sound is heard is the sum of the time
t
1
required for the stone to fall distance
h
and the time
t
2
required for sound to travel distance
h
in air on the
return up the well. That is,
t
1
+
t
2
= 2.00 s. The distance the stone falls, starting from rest, in time
t
1
is
2
1
2
gt
h
Also, the time for the sound to travel back up the well is
21
2.00 s
h
tt
v
Combining these two equations yields
2
11
2.00 s
2
g
v
With
2
337 m s and
9.80 m s
vg
, this becomes
2
1
2
1.45
10
s
2.00 s
0.
Applying the quadratic formula yields one positive solution of
t
1
= 1.95 s, so the depth of the well is
2
2
2
1
9.80 m s
1.95 s
18.6 m
22
gt
h
14.12
The decibel level due to the first siren is
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
2
1
12
2
100.0 W m
10 log
140 dB
1.0
10
W m
.
Thus, the decibel level of the sound from the ambulance is
21
10 dB
140 dB
10 dB
150 dB
14.16
(a)
From the defining equation of the decibel level,
0
10 log
II
. We solve for the intensity as
10
0
10
and find that
12
2
115 10
12 11.5
2
0.5
2
2
1.0
10
W m
10
1.0
10
W m
10
W m
0.316 W m
I
(b)
This is the end of the preview. Sign up
to
access the rest of the document.
 Winter '11
 ArmenN.Kocharian
 Physics, Work

Click to edit the document details