MEAM 203
SPRING 2007
THERMO  MIDTERM
I
Closed books.
One sheet with formulas is allowed.
Answer all questions.
Write clearly!
Explain all steps!
GOOD LUCK.
1.
(35%) A cylinder (B), capped with a frictionless,
freefloating piston, is connected to tank (A) by a
line equipped with a valve.
See the figure on the
right.
Initially, the valve is closed and tank A
contains ideal gas at pressure
p
A
and temperature
T
.
The volume of tank A is
V
A
.
Cylinder B is
empty.
The valve is opened and gas flows slowly
from A to B.
The piston begins to rise when the gas pressure in cylinder B reaches
p
B
(<p
A
B
B
A
)
.
The
process continues until the pressures in both tanks equalize. The process is isothermal.
Express all
your answers in terms
of
p
A
, p
B
B
, V
A
,
and
T
.
(10%)
(i)
What is the volume of the gas in tank B at the end of the process?
At the end of the process, the gas is at a uniform pressure
p
B
.
Initial mass equals final mass.
p
B
A
V
A
/RT=p
B
B
(V
A
+V
B
)/RT;
p
B
A
V
A
=p
B
B
(V
A
+V
B
);
V
B
B
B
=V
A
(p
A
/p
B
1)
B
(10%)
(ii)
Determine the work interaction during the process.
W=p
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 Spring '08
 Bau
 Thermodynamics, Heat, thermodynamic probability

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