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Unformatted text preview: Physics 222, Summer 2006 EXAM #2
Monday, July 10, 2006
Name (printed):
ID Number:
Section Number:
Recitation Instructor:
INSTRUCTIONS: 1. This is a onehour exam consisting of twenty multiplechoice questions. Each
question is worth I point; for a total of 20 points. 2. Use a number 2 pencil when marking your bubble sheet. Do not use ink. Ask
for a pencil if you did not bring one. Fill in the appropriate bubble completely.
If you need to change any entry, you must completely erase your previous entry.
Also, circle your answer on the exam. 3. Carefully read each problem and its ﬁve possible answers before beginning to
work on the problem. Select only one answer for each problem. Choose the
answer that is closest to the correct one. 4. Before handing in your exam, be sure that your answers on your bubble sheet
are what you intend them to be. Copy down your answers on a piece of a scratch
paper for comparison with the answer key to be posted later. 5. When you are ﬁnished with the exam, place all exams materials, including the
bubble sheet, the exam itself, and scratch paper that you used for the exam, in
your folder and return the folder. Good Luck! Exam 2 Formula Sheet :31: :1. 38x10 Z’J/K N 'L’é’diﬁm magma?) 111518 {EmmafﬁgfT515511???“ W—
F 1 1 ,
:p = ﬂP = ﬁPz = 1‘} +pgh;p1v1A1: 10211214511241 = 122141;}? +19% +—pvf = P2 + pgfe +—pvg; V A A 2 ” 2 '11 1n1i!2lF= ”if? IE‘b‘ii1ll1lk H‘Hi E1§IIHJ1H11 E y = A cos(a)t — Rx) for wave motion toward +x; y = A cos(a7t + be) for wave motion toward X P I r2 ”311 1 62y 22a) 27: andk=27ﬂrgP 5/ Fa; A2; I:—: 27;? 2 _ 2 f y A 472'1‘2 12 8162—21} Biz 2
1 ,1
:f=?;v:f}£ =?;f gnﬁ, nﬁ;.& :2L/n;v: L;v=331 1+2 : szkwAz :>Im=§BkmA2;13"_~ (10dB)log[Ii] 1291,1111}? vI—vo _
;] v_ vs 9
9 5 9 I} =§Tc+32;]: =—(2‘; ~32);ATT =§ATc;AT; = AYEJ; =1; +273.15;AL =LrL0AT;AV = ,BIQAT; T — . PV
Q: chT;H=“2= M H T1 ;Hne,=Aea(T4—TS4; = PVE
dt L T1 T2 mvl. zikﬂTw , : 3kBT; mm =nM;M:mN4;Average K” per moleule 2 111211123113? T; kg = 1; Average K” per mole ofgas = 1114an 23121"; vmp =11£§Vm—’:kT;:n=1/3—kf
NA 2 2 m Kmm5=N 11m); :ENkBT=§nRT;P=2[£][im i} NkMT/l Vt
2 2 2 3 V 2 — —;constant I‘1 Ii‘H'I1‘l11llilifixii‘lhlillr‘ ENFEIUJL I1¢U1lt ll “IN H1H1li':IEi‘i‘fH?H1IE1Hillll11lliil'I1‘lé1ll‘iMIiriltiF hilﬁlhIlvIl‘?.i11l51lli111!12!51ﬂ1 mum _ 2 m;
—47r\12 r N
1 W:P(V2 —V;);Q=AU+W;Q=nCVAT;Q_=nCPAT;CP —CV :R;y=FP;W =r1CV(T1 —T2)
1" 1211 1_KWQ(~_ 191.1 e=1a_ QHI *1W1‘1QH1—IQL1
W. T TH—z; T e:— 8(zme :lMA: ;K('(mmr : ;ASZ 2d—Q7S: king); AS: kh1_,AS>G,
QH TH TH TH ‘3'? 1 T ‘91 fdQ T1, Vf . .
:”CVmT—+ann~V'~;F=q(va);F:qusmgﬁgdlﬁ : IBC03¢dA;F=ILBsm¢; TV"! = constpV’ = const;W=~lI(P1V1 A #2)“? =1—
y— AS=1T mv qB E ‘JXBV 13 R 13 r=m;m:—;Vx—;T=NMBsin ;2: KB; :NIA;U:— .B;n 2 ';AV 2%: H ;
193 m B {15 H ,u 11 q E H nqt t . #ONI
3f2 ’Bx: ;qB' dl: AUDI maimed ”1:1?" IS‘JIHH “LIE' l1‘ {11 ii1 li'l§>i.§1 31:321 ill 11‘?!“ {1‘ UK”: E1 Il‘ I5? £1=Il1 IIC Itiil‘ 11‘“! Hi WW il' IVﬂl i111 .151 H? I1iii‘ Ii‘ ll. llii1fllx IF‘ “1 iii IN N1 l2? . _ H1 fl‘ £12 53111“ 1‘7 ll H1IFI§111 IF [Hilrli‘IEHH I11l!1Ii:§1ili1l‘lli‘ii6’§1 H' EL'ESP l1IE.5‘I1'I!1ﬁLliiiMiiFﬂ‘H: Choose the one alternative that best completes the statement or ansWe'rs the
question. 21 For an ideal gas the internal energy U depends only on
A) pressure. B entropy. D) volume; E) the amount of heat added to it. 22 A sealed tank contains 44 moles of an ideal gas, at an initial temperature of 270 K. The
pressure of the gas is increased until the ﬁnal pressure equals 1.9 times the initial pressure.
The heat capacity at constant pressure of the gas is C p—"27 0 meol. K. The change in the ~ 0 ""2 ’ 3
internal energy of the gas, in k] is closest to: ’P ﬂigﬁ ”in 1'— 2f 2”} [2” 5} K
' f2. A)290 73V SKIRT; inVIZLIﬂKIZJ> {PL r (2 I"?
3:810 , 71,12,373 5:3 2% : 242:4 g
D)110 (if :Jﬁ? :CV #flﬁ .9 CU .' C}? R: ﬁ¥~ 3/9 :Mx/J ZEZXﬂé'S A” .266. [<3 23— In the ﬁgure, an ideal gas is carried around the cyclic
process. How much work is done in one cycle( if P0 2 8 atm dV0t7 0 iitegW: 2 FL; Mfg/5+ MFA!) giiéﬁggi :7 28V _. P U ;; 56):; V sees. {as WM; )
:2: 5 £66 3 24 An adiabatic compression is performed on an ideal gas. The ﬁnal pressure is equal to
0.56 times the initial pressure and the ﬁnal volume equals 1.50 times the initial volume. The
adiabatic constant for the gas is closest to: ‘5
es: w w: +> Z; :— 32>
(3)152
31%“ .i :(W :> 1:496:05) (3% as In z.¥sé:\5lm 1‘5
(3:530:75'03'4‘65) “1522.,G‘Egé a. I 43
5405 .. ‘5 25 When an ideal gas is expanded in volume at constant pressure, the average kinetic energy of the gas molecules
A) decreases. C) does not change. D) may either increase or decrease, depending on whether or not the process is carried out
adiabatically. E) may or may not change, but insufﬁcient information is given at make such a determination. 26~ A diesel engine operates reversibly on the
cycle abcda, using 9.0 moles of an ideal gas.
Paths be and da are adiabatic processes. The adiabatic constant of the gas is 7/ =1 .50.
According to the ﬁgure, the work performed by
the engine, in the adiabatic expansion, in k], is
closest to: s C r/Cv "‘ 93] Mat;
B)24 (3)29 C I: : (:V’i‘ga , . , ‘
D)I3 gs inéi—vCﬁ Mg 629%? Mia/elk» E 19 1 _ . , i
) T : 51ml: T .. #32}: (Was 15+)» diatomic swag/15.2%
:> AT m Z/Ez—CWo : ... 105314 (l iwmﬂ/QLMC; % W3 NWAUZ"”CVA/:H Xi ‘£2§X(“‘lég.
o 9 4
(6 Kg} 27— A real (non—Carnot) heat engine, operating between heat reservoirs at temperatures of
670 K and 270K performs 3.1 k] of net work, and rejects 9.2 kJ of heat, in a single cycle. The
thermal efﬁciency of this heat engine is closest to: A) 0.20 f
B) 0.30 a ” Wear, :1 Q”
C) 0.23 ‘ Q H
D) 0.28 QH 0 KEY Gig .. Q'ZlCtl :> (CH ,;,+li.”z: l2 "5/ch
gs] 1: W ,____.4
"ﬁ": 223 KI : (1/23
I; 5 .. 28— The efficiency of a Carnot engine operating between 323°C and 700°C is A) 53.3% o.
B)616% t ‘7'; i 2¥3+323 :3333/3
T7? 6 p f" ,.__..—/_ 1’— '” ". 3 D)6l.7% (ma 11; 1200 *2? E) 32.3% 29— 36 moles of liquid helium (molar mass of helium = 4g/mol) are vaporized at its boiling
point of 4.22 K, at atmospheric pressare. The heat of vaporization of helium, at atmospheric
pressure, is 2.09x1031/kg. The change in the entropy of the helium as it vaporizes, in SI units,
is closest to: salt? as; . mt WW J” W” 0’?
015000 AS DE: (35232” ES)CQG‘3>UQ DA, izsoe
D)~—7500 :: W’v O r 2” 27’ 30~ Which of the following is FALSE statement?
A) Entmpy is a quantitative measure of the disorder of the system
B) Change in entropy depends on only the initial and ﬁnal states Cg Entropy of a macroscopic system having a) mierostates is S=kB Ina) E) Entropy, S, is a state variable of the thermodynamics system. 31 In the ﬁgure, if the magnetic
moment of the current ioop is
0.75 Amz, then the magnitude of
the magnetic torque exerted on the loop is closest to:
A) 0.55 N  m
C) 0.35 N  m
D) 0.25 N  m
E) 0.45 N  m 32 In the above ﬁgure, an external torque changes the orientation of the loop from one of
lowest potential energy to one of highest potential energy. The work done by the external torque is closest to: Q C) 15 J
A)0.SJ a: "‘3 ,.. , r 2 T5 1 035% (3,7 of «
2533: List ”3 — 7‘5"?“ C“ ’36 J‘ a 5 M :3"
. , ﬂ _ (Z .3 ...» i .
roe6.1 um: NEW ”‘5“ a 06:3”
0 LU: 0, ~U : oasrc‘hﬁw) " ‘i
Mi. Flo—wt 33 Which of the following is an accurate statement?
A) A magnetic ﬁeld line is, by deﬁnition, tangent to the direction of the magnetic force on a
moving charge at a given point in space.
B) A current carrying loop of wire tends to line up with its plane parallel to an external
magnetic ﬁeld in which it is positioned ) The rnagnetic force on a current carrying wire is greatest when the wire is parallel to the magnetic ﬁeld.
E) Magnetic ﬁeld lines have as their sources north and south poles. 34 A mass spectrograph is operated with deuterons, which have a charge of +e and a r _ .—
mass of3.34x1 0'27 kg. Deuterons emerge i G B I “53 T
ﬁ'om the source, which is grounded with gen utron I sou ice _ ___ _5 1 negligible velocity. The velocity of the
deuterons as they pass through the
accelerator grid is 8.0x105 m/s. A uniform I
magnetic ﬁeld of magnitude 0.20 T, directed T I
out of the plane, is present at the right of the grid. In the figure, the angular velocity of the i V = J 0 2o: 1 L15 mfs A‘v’a
accelerator grid deuterons in the magnetic ﬁeld is closest to: B
A)2.5 x 10?rad/s WW m # ____
B) 1.6X106rad/s Y” ; W :> W e “YT" ” m
C 4.0X106rad/s ‘P‘B 1?) C )_ mg/
_ it'll) C) Zn 7"
6.3 x107 rad/s L“ 1 ONE)? I 35 A solenoid is wound with 110 turns on a ,3____, ‘58 cm a,
form 4 cm in diameter and 50 cm long. The windings carry a current in the sense that is f
shown. The current produces a magnetic ﬁeld, 4 cm
of magnitude 2.5 mT at the center of the ill
solenoid. In the ﬁgure, the current in the
solenoid windings is closest to: I I
A) 11 A
B) 7.9 A N ‘
pr 4" ,— "— 3 m
D lOA (3 “fun“: ”/‘a(L) j: 2.5x“) 930‘;
1 0 v—“ __> 3: — . _ _.
E)68A  r3 F, . at L L — man; We
2.5}:10 1: thxla 2((‘3‘50 4 36 Three very long, straight, parallel wires each
carry currents of 4 A, directed out of the page in the
drawing in the ﬁgure. The wires pass through the
vertices of a right isosceles triangle of side 2 cm.
What is the magnitude of the magnetic ﬁeld at point
P at the midpoint of the hypotenuse of the triangle? gainleo‘ér ”B Calais: :52
C)l.77X10:T ’
D)1.26X10 T g C 33 E) 1.77 x 10'5 T mg}.
a]:
E3 3 fit.—
ZILY‘ F
_ 476m; xi; ...
A/VYU’ZXLEZ 37 A metallic weight is suspended from a metal spring. If now a current is passed through
the spring, A) the spring will extend, lowering the weight. B the weight will not move. D) whether or not the weight moves up or down depends on what the weight is made of (Le.
whether or not it is magnetizable)
E) None of these are true. 38 A circular coil of wire of 200 turns and diameter 5 cm carries a current of 4 A. It is
placed in a magnetic ﬁeld of 0.70 T with the plane of the coil making an angle of 30° with the magnetic ﬁeid. What is the torque on the coil? L, a A)2.5Nm go : 96% 3’0 : 66> B)0.48Nm 2.»: ”31,4333“wa Q C)0.55Nm 2? $44
D)1.8N'm _, 2.609(1" X3“iL/)€<*E_’Xi62 x0 X0 39 In the ﬁgure, what is the magnetic ﬁeld at the center
of the two concentric arcs? The inner arc is of radius 4
cm and the outer arc is of radius 6 cm. The loop carries a current of 4 A. G I _' AT_
A)4.45x10‘51‘ ‘3 ”5 gc: Xﬂ/‘”E§Lﬂ‘i‘ ’\ ‘ "\
B)2.09x10'5'r 35“ (ii 1.5qu 7‘
C)7.95x10*5T A {“61 9, M,” an t 1 K1
. q; » 3i: ._ 239/0“ ‘Q/
E)7.14x104T Li H (K: .
(E1 1 [*0 Qﬁggzrécm
[17C 7,
MI
(E ; E?" 32 ‘ éziﬁ
.. 3 1;? w; T 40 In the ﬁgure, a wire is bent into the shape of an
Omega, with a circular loop of radius 4.0 cm and two
long straight sections. The loop is in the x—y plane with
the center at the origin. The straight sections are parallei
to the xaxis. The wire carries a 5 A current, as shown.
The magnitude of the magnetic ﬁeld at the center of the loop, in “T is closest to: A)80
19940 {B #32451) is
C) 105 _‘ 61 ﬂ kl] @25 ~ 1 21:7? 2 R ,i.‘ Answer No. Answer No. 31 21 32 22 33 23 34 24 35 25 36
37 26
27 FF 38 28 39 29 49 30 ...
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