Thermodynamics PowerPoint

mistaureolinMechanics

Oct 27, 2013 (4 years and 17 days ago)

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What is the ratio
T
f
/
T
i

for this process?

A.
4

B.
2

C.
1 (no change)

D.


E.



What is the ratio
T
f
/
T
i

for this process?

A.
4

B.
2

C.
1 (no change)

D.


E.



A gas cylinder and piston are covered with heavy insulation.
The piston is pushed into the cylinder, compressing the gas.
In this process, the gas temperature

A.
doesn’t change.

B.
decreases.

C.
increases.

D.
there’s not sufficient information to tell.

A gas cylinder and piston are covered with heavy insulation.
The piston is pushed into the cylinder, compressing the gas.
In this process, the gas temperature

A.
doesn’t change.

B.
decreases.

C.
increases.

D.
there’s not sufficient information to tell.

Two process are shown that take an ideal gas from state 1
to state 3. Compare the work done by process A to the
work done by process B.

A.

W
A

=
W
B

= 0

B.

W
A

>
W
B

C.

W
A

=
W
B

but neither is zero

D.

W
A

<
W
B


Two process are shown that take an ideal gas from state 1
to state 3. Compare the work done by process A to the
work done by process B.

A.

W
A

=
W
B

= 0

B.

W
A

>
W
B

C.

W
A

=
W
B

but neither is zero

D.

W
A

<
W
B


Which of the following processes involve heat?

A.
The brakes in your car get hot when you stop.

B.
A steel block is placed under a candle.

C.
You push a rigid cylinder of gas across a frictionless
surface.

D.
You push a piston into a cylinder of gas, increasing
the temperature of the gas.

E.
A gas
-
filled, uninsulated cylinder is immersed in ice
water. The piston is covered with pellets that you
slowly remove. The gas expands, causing the piston
to rise. The temperature of the gas remains at 0
°
C.


Which of the following processes involve heat?

A.
The brakes in your car get hot when you stop.

B.
A steel block is placed under a candle.

C.
You push a rigid cylinder of gas across a frictionless
surface.

D.
You push a piston into a cylinder of gas, increasing
the temperature of the gas.

E.
A gas
-
filled, uninsulated cylinder is immersed in
ice water. The piston is covered with pellets that
you slowly remove. The gas expands, causing the
piston to rise. The temperature of the gas remains
at 0
°
C.

The gas does work on the piston, so it loses energy. The
thermal energy must remain the same for the
temperature to remain fixed, so there must be heat
transfer from the ice water to the gas. There will be an
increase in the amount of ice in this process.

Which first
-
law bar chart describes the
process shown in the
pV

diagram?

Which first
-
law bar chart describes the
process shown in the
pV

diagram?

For the two processes shown, which of the following
is true:

A.

Q
A

<
Q
B
.

B.

Q
A

=
Q
B
.

C.

Q
A

>
Q
B
.

For the two processes shown, which of the following
is true:

A.

Q
A

<
Q
B
.

B.

Q
A

=
Q
B
.

C.

Q
A

>
Q
B
.

A.
1 mol of He at
p

= 1 atm,
T

= 300 K

B.
2 mol of N
2

at
p

= 0.5 atm,
T

= 450 K

C.
2 mol of He at
p

= 2 atm,
T

= 300 K

D.
1 mol of Ar at
p

= 0.5 atm,
T

= 450 K

E.
1 mol of N
2

at
p

= 0.5 atm,
T

= 600 K

Which system has the largest average translational kinetic
energy per molecule?

Which system has the largest average translational kinetic
energy per molecule?

A.
1 mol of He at
p

= 1 atm,
T

= 300 K

B.
2 mol of N
2

at
p

= 0.5 atm,
T

= 450 K

C.
2 mol of He at
p

= 2 atm,
T

= 300 K

D.
1 mol of Ar at
p

= 0.5 atm,
T

= 450 K

E.
1 mol of N
2

at
p

= 0.5 atm,
T

= 600 K

What is the thermal efficiency of this heat engine?

A.
0.10

B.
0.25

C.
0.50

D.
4

E.
Can’t tell without knowing
Q
C
.

What is the thermal efficiency of this heat engine?

A.
0.10

B.
0.25

C.
0.50

D.
4

E.
Can’t tell without knowing
Q
C
.

What, if anything, is
wrong with this
refrigerator?

A.

It violates the first law of thermodynamics.

B.

It violates the second law of thermodynamics.

C.

It violates the third law of thermodynamics.

D.

It’s impossible to tell without knowing what kind of
cycle it uses.

E.

Nothing is wrong.

What, if anything, is
wrong with this
refrigerator?

A.

It violates the first law of thermodynamics.

B.

It violates the second law of thermodynamics.

C.

It violates the third law of thermodynamics.

D.

It’s impossible to tell without knowing what kind
of cycle it uses.

E.

Nothing is wrong.

Δ
E
th

= Q + W
in

by the first law and
Δ
E
th

= 0 for a cycle. We
have
Δ
Eth = (40


30) + 10 = 20 J for a cycle.

What, if anything, is
wrong with this
engine cycle?


A.
It violates the first law of thermodynamics.

B.
It violates the second law of
thermodynamics.

C.
It violates the third law of thermodynamics.

D.
It’s impossible to tell without knowing what
kind of cycle it uses.

E.
Nothing is wrong.

What, if anything, is
wrong with this
engine cycle?

A.
It violates the first law of thermodynamics.

B.
It violates the second law of thermodynamics.

C.
It violates the third law of thermodynamics.

D.
It’s impossible to tell without knowing what kind of cycle it uses.

E.
Nothing is wrong.

One version of the second law states that no cycle operating
between a given two temperature extremes can exceed the
efficiency of a Carnot cycle operating between the same two
temperature extremes. e
carnot

= 1


T
c
/T
h

= 1


300/600 =
0.50 and e = W/Q
h

= 60/100 = 0.60.