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Unformatted text preview: MC True/False Q 10 24/ 1 0/ 1 0/ 90/
Fall 2004 Last Name Physics 2750 Exam #4 First Name ID# Points for each question are indicated in parentheses. F or full credit show your work for solutions to
questions that require calculations. Explain from where you start to solve the problem and show your
math ﬂowing from it for full credit. If you need more space to ﬁnish a question, write BPP (Back of the
Previous Page) at the end of the space provided and then complete your work on the back of the previous
page. For multiple choice questions, circle the letter for the answer which you believe to be correct. Do
not forget to change your calculator from degrees to radians as needed. In all problems take the
gravitational acceleration g = 10 m/sz. Each multiple choice question is worth 3 points. 1. The work done in the expansion from an initial to a ﬁnal state
a) depends only on the end point
b) is independent of the path
c) is the slope of a PV curve d equals pAV
@ is the area under the curve of a PV diagram 2. Which of the following statements is correct?
You only need to know the amount of thermal energy a body contains to calculate its temperature.
b) The temperature of a body is directly proportional to the amount of work the body has performed.
c) Different amounts of thermal energy are transferred between two bodies in contact if different
temperature scales are used to measure the temperature difference between the bodies.
d) When an ideal gas is subjected to an isothermal process, no heat is supplied to the system
e) The heat capacity of a body is the amount of heat it can store at a given temperature 3. Two containers hold an ideal gas at the same temperature and pressure. Both containers hold the same
type of gas but container B has twice the volume of container A. The average translational kinetic energy per molecule in container B is ' g \ ‘
a Twice that for container A K C k5 T i Pr — T5
@The same as that for container A
c Half that for container A
d) Impossible to determine 4. If a system’s volume remains constant while undergoing changes in temperature and pressure, then
a The internal energy of the system is unchanged
The system does no work
c The system absorbs no heat The change in internal energy equals the heat absorbed by the system 5. Two containers have identical gases, initially at the same temperature, pressure and volume. The two
containers are placed on a stove. If container A has a ﬁxed volume and container B keeps the pressure
contnt (but the volume changes), the gas in which container will heat up more quickly?
Container A
V b) Container B
c) The gas in both containers will heat up at the same rate. 6. The wave function of a harmonic wave on a string is y(x,t) = 0.004 sin(59.7x + 293t), where x and y
are in m and t is in s. What is the speed and direction of the wave (taking positive to be in the +x
direction and negative in the —x direction) a) 491m in 29% N ~ ‘M b) 0.128m/ = I: :—‘~ = WM 5 NW ‘ ;, r
c) Om/s S \Q. 533' / V\ gm, gimciiem A 0.125 m/s
@ 4.91 m/s 7. The diagram at right represents a periodic wave.
Which two points on the wave are in phase?
a) A and D b AandG
@CandK
d) DandI
'e) CandI 8. In air, where the speed of sound is 340 m/s, the frequency of a particular sound wave is 680 Hz. When
this sound enters water, where its speed is 1540 m/s, its wavelength will be: a) 0.5m @ 2'26 m 3&0)“: 7LO;N l/mer Admoik \5MO
c) 3.4 m :5 (A, [NOA— = _ = 1 N.
d) 1.24m Hwy: Rwy£0,” £0»: 6 9. Please circle T for True and F for False for the following statements: @ F a) The average translational kinetic energy of the molecules of an ideal gas depends on the
number of moles of the gas and its temperature b) A 60 dB sound has twice the intensity of a 30 dB sound. T (F)
T ® c) Water ﬂows through a pipe having a varying width. More water ﬂows per second
through the wide section than through the narrow section because there is more room
63 for it to ﬂow.
F
T e) if the hydrostatic pressure at a certain depth in the ocean is 2 atm, the hydrostatic
' pressure will be 4 atm if you go twice as deep (1) A system can absorb heat with no change in its internal energy 10. In a section of horizontal pipe with a diameter of 3.00 cm the pressure is 100 kPa and water is
ﬂowing with a speed of 1.50 m/s. The pipe narrows to 2.00 cm. What is the pressure in the narrower region? A KW? Q g 1—
‘, K t, , . I. 5: 7p t;
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AW 2/ v 01 A1 \ z 2mg, [aw—“M \M ){lcaaré /§. 11. A truck moving at 30 m/s passes a police car moving 45 m/s headed in the opposite direction. If the
frequency of the police car siren is 500 Hz relative to the police car, what is the change in frequency (in
Hz) heard by an observer in the truck as the two vehicles pass each other? (Take the speed of sound in air to be 340 m/s.) XUL + A71
if: kii‘SOD’lf‘w pffgo, Vi: $955 5+?“ sag—E,  3M0 +30
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W 12. A sample of a monoatomic ideal gas that occupies 5.0 L at atmospheric pressure and 300 K
temperature, is heated at constant volume to a pressure of 3 atm. Then it is allowed to expand
isothermally to 1 atm and at last is compressed isobarically to its original state.
Consider 1 atm = 105 N/m2 and R = 8 J/mol K. a) Draw the cycle in the PV diagram provided b) Find the number of moles in the gas sample c) Find P, V, T for each one of the three states and ﬁll in the values in the table below d) In which process is heat absorbed and in which is released? X>i02 Rmﬁrﬁ%&&
We}? ©\3m_\m& \ Mm} (th%& 1%3 13. A 5 g piece of ice at 10C is placed in an insulated container with 100 g of water at 100°C. The
speciﬁc heat is 2050 J/kgK for ice, 4160 J/kgK for water and the latent heat of fusion for water is 333
kJ/K. a) When thermal equilibrium is established, what is the ﬁnal temperature of the water? b) Find the
entropy change of the ice during the phase transition. 0% @stgoc z weW (0035 : [5.6% (2050\(ﬁz “3.26 Qicevvwﬂ‘t: W,\71W:L6‘\653L3%5'l03> z HOCDSQY
nglusoﬂc/ = N2 Cl [co—TA 2 (oil) (u\%0\@~loo§ 2 4M 3 Bang,
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W M ‘ o W:
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:> 202)ch + Lu, (0'1; : Lll>l900‘ [($05 \0.'2.5 W :3 = 9H; Q MA
—_ —_ if“ T‘ 7213
W W M 15> AS: N Qwexmdlf __\ t I Bonus question: (5 points)
Can a temperature be assigned to a vacuum? Explain your answer. ...
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 Spring '08
 kozstin
 Physics, Thermodynamics, Energy, police car, translational kinetic energy

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