Patel, Kinal – Homework 22 – Due: Nov 30 2007, 7:00 pm – Inst: D Weathers
1
This
printout
should
have
11
questions.
Multiplechoice questions may continue on
the next column or page – find all choices
before answering.
The due time is Central
time.
001
(part 1 of 1) 10 points
A car tire gauge is used to fill a tire to a gauge
pressure of 42
.
5 lb
/
in
2
on a cold morning
when the temperature is

9
◦
C. Atmospheric
pressure is 14
.
7 lb
/
in
2
and 0
◦
C = 273 K.
What would the tire gauge read when the
tire has been heated up to 30
.
5
◦
C?
Correct answer: 51
.
0583 lb
/
in
2
.
Explanation:
Given :
P
atm
= 1 atm = 14
.
7 lb
/
in
2
,
P
1
g
= 42
.
5 lb
/
in
2
,
T
1
=

9
◦
C = 264 K
,
and
T
2
= 30
.
5
◦
C = 303
.
5 K
.
Since the rubber is not expanding, the volume
stays fixed. From the ideal gas law
P V
=
n R T
and
P
1
=
P
1
g
+
P
atm
= 42
.
5 lb
/
in
2
+ 14
.
7 lb
/
in
2
= 57
.
2 lb
/
in
2
,
so
P
1
V
T
1
=
P
2
V
T
2
P
2
=
P
1
T
2
T
1
P
2
g
+
P
atm
=
P
1
T
2
T
1
P
2
g
=
P
1
T
2
T
1

P
atm
=
(57
.
2 lb
/
in
2
) (303
.
5 K)
264 K

14
.
7 lb
/
in
2
=
51
.
0583 lb
/
in
2
.
keywords:
002
(part 1 of 1) 10 points
At 24 m below the surface of the sea (den
sity of 1223 kg
/
m
3
), where the temperature
is 4
◦
C, a diver exhales an air bubble having a
volume of 0
.
4 cm
3
.
The acceleration of gravity is 9
.
8 m
/
s
2
and
the atmospheric pressure is 102000 Pa.
If the surface temperature of the sea is 18
◦
C,
what is the volume of the bubble immediately
before it breaks the surface?
Correct answer: 1
.
60527 cm
3
.
Explanation:
Given :
L
= 24 m
,
ρ
= 1223 kg
/
m
3
,
T
1
= 4
◦
C = 277 K
,
V
1
= 0
.
4 cm
3
,
and
T
2
= 18
◦
C = 291 K
.
At depth
L
P
=
P
a
+
ρ g L
and
P V
1
=
n R T
1
.
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 Spring '07
 Weathers
 Thermodynamics, Energy, Work, Correct Answer, patel

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