Transcript – Thermal Physics AP Physics Review Ch 12-15 

AP Physics Review Ch 12-15 – Thermal Physics
•
•
•
•
•
•
•
Linear and volumetric expansion
Difference between conduction and convection
Factors that affect rate of heat transfer; H  AT/L
Kinetic theory of gases; T Kavg  v2rms
Ideal gas law
Heat vs. internal energy
Four thermal processes
1.
2.
3.
4.
Isobaric
Isochoric
Isothermal
Adiabatic
•
Cyclic processes (know difference between heat engine and
refrigerator)
•
•
Efficiency
Maximum efficiency (Carnot’s theorem)
Which system has the largest average translational kinetic
energy?
A. 1 mol of He at p = 1 atm, T = 300 K
B. 2 mol of N2 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 N2 at p = 0.5 atm, T = 600 K
Which system has the largest average translational kinetic
energy?
A. 1 mol of He at p = 1 atm, T = 300 K
B. 2 mol of N2 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 N2 at p = 0.5 atm, T = 600 K
Metals such as steel expand when heated. A thin steel
plate has a circular hole in its center. When the plate
is heated, what will happen to the hole?
(A) gets larger
(B) gets smaller
(C) stays the same
(D) vanishes
Metals such as steel expand when heated. A thin steel
plate has a circular hole in its center. When the plate
is heated, what will happen to the hole?
(A) gets larger
(B) gets smaller
(C) stays the same
(D) vanishes
What is the ratio Tf /Ti
for this process?
A. 4
B. 2
C. 1 (no change)
D.
E.
What is the ratio Tf /Ti
for this process?
A. 4
B. 2
C. 1 (no change)
D.
E.
Two cylinders at the same temperature contain the same gas. If
B has twice the volume and half the number of moles as A, how
does the pressure in B compare with the pressure in A?
(A) PB = 1/2 PA
(B) PB = 2 PA
(C) PB = 1/4 PA
(D) PB = 4 PA
(E) PB = PA
Two cylinders at the same temperature contain the same gas. If
B has twice the volume and half the number of moles as A, how
does the pressure in B compare with the pressure in A?
(A) PB = 1/2 PA
(B) PB = 2 PA
(C) PB = 1/4 PA
(D) PB = 4 PA
(E) PB = PA
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.
During an isothermal process, 5.0 J of heat is removed from
an ideal gas. What is the change in internal energy?
A) zero
B) 2.5 J
C) 5.0 J
D) 10 J
During an isothermal process, 5.0 J of heat is removed from
an ideal gas. What is the change in internal energy?
A) zero
B) 2.5 J
C) 5.0 J
D) 10 J
The Laws of Thermodynamics
If the gas in a container absorbs 300 J of heat,
has 100 J of work done on it, and then does
200 J of work on its surroundings, what is the
increase in the internal energy of the gas?
(A) 600 J
(B) 400 J
(C) 0 J
(D) 500 J
(E) 200 J
If the gas in a container absorbs 300 J of heat,
has 100 J of work done on it, and then does 200
J of work on its surroundings, what is the
increase in the internal energy of the gas?
(A) 600 J
(B) 400 J
(C) 0 J
(D) 500 J
(E) 200 J
If three identical samples of an ideal gas are taken from initial state I to
final state F along the paths IAF, IF, and IBF as shown in the pV-diagram
above. Which of the following statements must be true?
(A) Point F is at a higher temperature than point B.
(B) No work is done by the gas along path IF.
(C) The change in temperature of the gas is the same for all three paths.
(D) The work done by the gas is the same for all three paths.
(E) The expansion along path IF is isothermal.
If three identical samples of an ideal gas are taken from initial
state I to final state F along the paths IAF, IF, and IBF as shown in
the pV-diagram above. Which of the following statements must
be true?
(A) Point F is at a higher temperature than point B.
(B) No work is done by the gas along path IF.
(C) The change in temperature of the gas is the same for all
three paths.
(D) The work done by the gas is the same for all three paths.
(E) The expansion along path IF is isothermal.
For the two processes shown, which of the following
is true:
A. QA < QB.
B. QA = QB.
C. QA > QB.
For the two processes shown, which of the following
is true:
A. QA < QB.
B. QA = QB.
C. QA > QB.
The maximum efficiency of a heat engine that
operates between temperatures of 1000 K in
the firing chamber and 600 K in the exhaust
chamber is most nearly
(A) 33%
(B) 40%
(C) 60%
(D) 67%
(E) 100%
The maximum efficiency of a heat engine that
operates between temperatures of 1000 K in the
firing chamber and 600 K in the exhaust
chamber is most nearly
(A) 33%
(B) 40%
(C) 60%
(D) 67%
(E) 100%
Two objects are made of the same material, but have
different masses and temperatures. If the objects are
brought into thermal contact, which one will have the greater
temperature change?
(A) the one with the higher initial temperature
(B) the one with the lower initial temperature
(C) the one with the greater mass
(D) the one with the smaller mass
(E) the one with the higher specific heat
Two objects are made of the same material, but have
different masses and temperatures. If the objects are
brought into thermal contact, which one will have the greater
temperature change?
(A) the one with the higher initial temperature
(B) the one with the lower initial temperature
(C) the one with the greater mass
(D) the one with the smaller mass
(E) the one with the higher specific heat
If you add some heat to a substance, is it possible for
the temperature of the substance to remain
unchanged?
(A) yes
(B) no
If you add some heat to a substance, is it possible for
the temperature of the substance to remain
unchanged?
(A) yes
(B) no
You may notice that if a mercury-in-glass thermometer is
inserted into a hot liquid, the mercury column first drops,
and then later starts to rise (as you expect). How do you
explain this drop?
(A) the mercury contracts before the glass contracts
(B) the glass contracts before the mercury contracts
(C) the mercury contracts before the glass expands
(D) the glass expands before the mercury expands
(E) the mercury expands before the glass contracts
You may notice that if a mercury-in-glass thermometer is
inserted into a hot liquid, the mercury column first drops,
and then later starts to rise (as you expect). How do you
explain this drop?
(A) the mercury contracts before the glass contracts
(B) the glass contracts before the mercury contracts
(C) the mercury contracts before the glass expands
(D) the glass expands before the mercury expands
(E) the mercury expands before the glass contracts
A steel ring stands on edge with a rod of some
material inside. As this system is heated, for
which of the following rod materials will the
rod eventually touch the top of the ring?
(A) aluminum
(B) steel
(C) glass
Quartz
Glass Steel Al
Hg
Air




Coefficient of volume expansion b (1/°C )
A steel ring stands on edge with a rod of some
material inside. As this system is heated, for
which of the following rod materials will the
rod eventually touch the top of the ring?
(A) aluminum
(B) steel
(C) glass
Quartz
Glass Steel Al
Hg
Air




Coefficient of volume expansion b (1/°C )
A grandfather clock uses a brass pendulum to keep
perfect time at room temperature. If the air
conditioning breaks down on a very hot summer day,
how will the grandfather clock be affected?
(A) clock will run slower than usual
(B) clock will still keep perfect time
(C) clock will run faster than usual
A grandfather clock uses a brass pendulum to keep
perfect time at room temperature. If the air
conditioning breaks down on a very hot summer day,
how will the grandfather clock be affected?
(A) clock will run slower than usual
(B) clock will still keep perfect time
(C) clock will run faster than usual
Two cylinders at the same temperature contain the same gas. If
B has twice the volume and half the number of moles as A, how
does the pressure in B compare with the pressure in A?
(A) PB = 1/2 PA
(B) PB = 2 PA
(C) PB = 1/4 PA
(D) PB = 4 PA
(D) PB = PA
Two cylinders at the same temperature contain the same gas. If
B has twice the volume and half the number of moles as A, how
does the pressure in B compare with the pressure in A?
(A) PB = 1/2 PA
(B) PB = 2 PA
(C) PB = 1/4 PA
(D) PB = 4 PA
(D) PB = PA
In the closed thermodynamic cycle shown in
the P-V diagram, the work done on the gas is:
1) positive
P
2) zero
3) negative
V
In the closed thermodynamic cycle shown in
the P-V diagram, the work done on the gas is:
1) positive
P
2) zero
3) negative
V
The process shown on
the T-V graph is an
T
(A) adiabatic compression.
(B) isothermal compression.
(C) isochoric compression.
(D) isobaric compression.
o
V
The process shown on
the T-V graph is an
T
(A) adiabatic compression.
(B) isothermal compression.
(C) isochoric compression.
(D) isobaric compression.
o
V
An ideal gas is compressed to one-half its original volume
during an isothermal process. The final pressure of the gas
(A) increases to twice its original value.
(B) increases to less than twice its original value.
(C) increases to more than twice its original value.
(D) does not change.
An ideal gas is compressed to one-half its original volume
during an isothermal process. The final pressure of the gas
(A) increases to twice its original value.
(B) increases to less than twice its original value.
(C) increases to more than twice its original value.
(D) does not change.
Is it possible to transfer heat from a hot reservoir to a
cold reservoir?
(A) No.
(B) Yes; this will happen naturally.
(C) Yes, but work will have to be done.
(D) Theoretically yes, but it hasn't been accomplished yet.
Is it possible to transfer heat from a hot reservoir to a
cold reservoir?
(A) No.
(B) Yes; this will happen naturally.
(C) Yes, but work will have to be done.
(D) Theoretically yes, but it hasn't been accomplished yet.
Is it possible to transfer heat from a cold reservoir to a
hot reservoir?
(A) No.
(B) Yes; this will happen naturally.
(C) Yes, but work will have to be done.
(D) Theoretically yes, but it hasn't been accomplished yet.
Is it possible to transfer heat from a cold reservoir to a
hot reservoir?
(A) No.
(B) Yes; this will happen naturally.
(C) Yes, but work will have to be done.
(D) Theoretically yes, but it hasn't been accomplished yet.
A gas is taken through the cycle illustrated here. During one
cycle, how much work is done on the gas?
(A) -PV
P
2P
(B) -2PV
(C) -3PV
(D) -4PV
P
o
V 2V
3V 4V
V
A gas is taken through the cycle illustrated here. During one
cycle, how much work is done on the gas?
(A) -PV
P
2P
(B) -2PV
(C) -3PV
(D) -4PV
P
o
V 2V
3V 4V
V