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Unformatted text preview: ' Sou/Tum $  _ PHYSICS 222 "Fall 2010
EXAM 1: September 30, 2010 3:00pm—10:00p'm Name (printedl: Recitation instructor; Section ll ' INSTRUCTIONS: This exam contains 25 multiplechoice questions, plus two extracredit questions, each worth 3 points. Choose
one answer only for each question. Choose the best ansWer to each question. Answer all questions. Allowed material: Before turning over this page, put away all materials except for pencils, erasers, rulers and your
calculator. There is a formula sheet attached at the end of the exam. Other copies of the formula sheet are not
allowed. Calculator: In general, any calculator, including calculators that perform graphing, is permitted. Electronic devices
that can store large amounts of text, data or equations {like laptops, palmtops, pocket computers, PDA or ebook
readers) are NOT permitted. if you are unsure whether or not your calculator is allowed for the exam, ask your TA. How to fill in the bubble sheet:
Use a number 2 pencil. Do NOT use ink. if you did not bring a pencil, ask for one.
Write and fill in the bubbles corresponding to:
— Your last name, middle initial, and first name. ~ * * Your ID number (the middle 9 digits on yourlSU card! ﬁr ﬁr  Special codes K to L are your recitation section. (Honors sections: H1 9 10 ,' H2 9 23). Always use
two digits (e.g. 01, 09, 11, 13) ' ' Please turn over your bubble sheet when you are not writing on it. if you need to change any entry, you must completely erase your previous entry. Also, circle your answers on this
exam. Before handing in your exam, be sure that your answers on your bubble sheet are what you intend them to
be. You may also copy down your answers on a piece of paper to take with you and compare with the posted
anSWErs. You may use the table at the end of the exam for this. When you are finished with the exam, place all exam materials, including the bubble sheet, and the exam itself,
into your folder and return the folder to your recitation instructor. No cellphone callsailowed. Either turn off your cell phone or leave it at home. Anyone answering (or using) a cell
phone must hand in their Workimmediately; their exam is over. Best of luck, Poul Confieid and Paula Herrera 1. What is the absolute pressure (not gauge pressure) at the bottom of a beaker filled with mercury
that is 10.0 cm deep? Take patm = 1.01 x 105 Pa. (See formula sheet for densities). A. 0.13 x 105 Pa
3. _ 0.87 x 105 Pa 1.14 x 105 Pa
“0. 8.72 x 105 Pa
E. 14.3 x 105 Pa 2. A 2.00 kg sphere is made out of a plastic that has a density of 900 kg/ma. What minimum outer
diameter does the sphere have to have so as to float on. water? (The sphere can be hoilow if
necessary.) (See formula sheet for densities). A. It will always sink
8. 7.82 cm
C. 15.6 cm
p. 24.3 cm It will always float 3. A U—shaped tube open on both sides contains water. Each arm has a 30cm high column of water in ' it. A 10cm column of oil (density 800 kg/rnB) is added to one arm. How high is the column of water
in the arm that has no of! added to it, when the system is in equilibrium? A.. 28cm
13. 30 cm 4 z ._ I
'. 32 cm ' .  . l m Al X. w lg “U f; (:7?)
‘M {V} 9 l M” m
i ; 4 , 3: ' k /
1‘ Vi] 4’ :3; "5’ l r Cﬂ‘i /l
“m, i 4. During a big storm a 60 km/h wind hiatus across the surface of a 2.00 m x 1.00 m window. What is
the force on the window associated with this wind? (See formula sheet for densities). A. 333 N pointed toward the inside of the house 333 N. pointed toward the outside of the house
C. 3000 N pointed toward the inside ofthe house D. 3000 N pointed toward the outside of the house Inside of Wind
E' O N Since the Wind: is along the plane of the window house . .
\ blOWIng
l‘ e mo 1.
“A + C) = +— //
Pal—Lu l l 2.
l ( {V} f)
. t l :3 l l r) ( 60 ,Cl .
...~ . 3 ﬂ 2 r; N ' % 2—— 1 Z \ _.»’ “a 1'3 l Lip," i: ., A (Ti 61 (f .3 3%?) 3 cl tattle, 5. A large cylindrical container with a base radius of 10.0 m filled
with water up to a level 11 = 6.00 m is being emptied with a siphon hose with a 10.0 cm diameter whose end is 3.00 m below
the bottom of the container (see figure). Determine the speed
of water as it exits the hose. 6.0 m
A. 3.94 m/s
B. 5.10 m/s
C. 7.67 m/s 6. An inﬂated balloon with a total mass of BOOg and a volume of 500 cm3 is attached to the bottom of a pool with a cable. The pool is filled with water, and the balloon is fully submerged. Findthe
tension in the cable. 5A." 1.96N ..,._ . 2.94 N W . 2: "‘33
c 4.91 N i
o 7.85 N l
E 9.81 N = 7. A 3.00g mass'has a —4.00 tLC charge on it. lfthe mass is released, in vacuum, near the Earth’s
surface, what electric field is necessary to create a zero net force on the mass? ' ' ' ' T— A. 7.35 N/C pointing up V
B. 7.35 x 103 N/C pointing up 7.35 x 103 N/C pointing down r“
o. 7.35 x 10“ N/C pointing up ‘ £3"
E. 7.35 xx 10'5 MC pointing down . _ ' 8. A metal bar has a cross section A. and length Li. In this form, the bar has a resistance R5. The whole
bar is now reshaped into a wire with a cross sectional. area ofAr = Ali/1000, turning aIE the initial mass
to fine wire. What is the resistance of the new long wire, in terms of Re? 105 R] \ [ a M M (M "M r $31k .2: r173 W31.
 ILX 7‘3 )ktqul r; I \f‘i‘vgﬁ 2‘ ‘ K i : '\ ‘h—M”  W V m ‘ '
B. 103R; J“ "‘ ‘—
c. R.
D. 10'3 R; t a  _ [ ,le T
E. 10'6 R1 LL [ ‘L " L" “F ,ﬁ
u 0 9. A charge is placed at the origin ofthe coordinate systems shown below. The magnitude_of_the
electrostatic force on the charge is greatest for: 10. A half circular ring (radius R} made of a thin plastic rod has a total charge Q spread evenly over its
length. What is the magnitude of the electric field at the center of the circle? , .jx (J . — a 3;”.
11. A flat surface (10 cm X 20 cm) is on the xz plane, in a uniform electric field E =(4000i +BOOOJ'). What
is the magnitude of the electric flux through the Surface? p A 50 le/c . .. z _ «v
B. so NmZ/C " c. 100 NmZ/C 7 v? .4; N .1»
D. 120 Nmz/c r” —_ . .A z (5 (:2. 61"“? ,
E 150 NmZ/C ~~“' C ./, == l 5U l C} : $an A 3 "02m 12. Which of the following statements about charges GA, 03, Q: is consistent with the field lines shown
beiow? [QB :4 [QM > [Qc; an is positive and QA and Q: are negative
E. IQBI > IQAI > lad; QB is negative and QA and Qc are positive
C. 1051: WA! '‘ Ich: QC is positive and QA and on are negative
D. ]QBE < QA < jacj; Q: is positive and QA and QB are negative
E. QB < QA < lac]; Q: is negative and QA and QB are positive. 13'. A water molecule has a dipole moment equivalent to having a proton and an electron separated by
4.00 x 10'11 m. Let the dipole be centered on the origin of an xy plane and be in a uniform electric field, LE =1000i N/C . What is the size and direction of the torque on the dipole? A. 6.40 x 10‘27 Nm, out of the page.
a. 6.40 x 10'27 f Nm C 2.19 x 10‘27 Nm, into the page. D 2.19 x 10‘27 iNm None of the above.
T: ,7)”
= 6.9%?) ‘U i T, )4. \Ciw‘fK my} l 9‘ . ' s ,i' 14. Two charges C21 = 3.00 C and Q; = —S.00 C are fixed. on the x axis at X; = 0 and x2 = +2.00. m,
respectively. At which point along the x axis {other than ice) is the net electric field zero? x=—6.87 m B. X: —0.873 m
C. x = +0873 m
D. x = +6.87 m E. There is no point along the x axis where the electric field is zero (except :00). ‘_ _.,...mn.a2< “ESQ Al 79/ fell; L :7: (Hula .. ii 15. The plots I and il below are best associated with : Pint I Plot II A. l  the electric field from a uniformly charged insulating sphere
il — the electric potential from a uniformly charged insulating sphere B. i» the electric potential from a charged metallic sphere
ll ——the electric field from a charged metallic sphere .43 /‘<
@l — the electric potential from a charged metallic sphere
” — the electric field from a uniformly charged insulating sphere D. l'  the electric potential from a charged metallic sphere
II the electric potential from a uniformly charged insulating sphere E.   the electric field from a charged metallic sphere
ll — the electric field from a uniformly charged insulating sphere Chair 3:. ; ( i" C) 1‘33“ 5 If u WI 7‘ H”? M' ‘~ . . ' I " gull—Eli 16. A parallei piate capacitor has an area of 5.00 x 5.00 cm2 and a separation of 2.00 mm.' When the space between the plates. is. empty, it has a capacitance, C*. A LOOmm thick sheet of rubber (g:
3.00) with the same area is inserted into the void space (filling half of it). What is the new I capacitance of the device in terms of C*? 2: FR“. olé ARMas (as "E? 3c*/2 " " r l »
(BJ 29 71 , a. cycle {I “’7 EILQLD
 i
E. 30*
C2,. ; 17. Which of the following is necessarily true for a conductor in equilibrium? A. E=0 inside,@everywhere.4 : Cl‘ i€,lf‘§f%3 Us 9. lS. . 03 E: 0 inside, V: O on the surface.
9. c (C/lAny EXCESS Charge is all 0" the surface, the surface is an equipotential. 2 I V I
0. Net electric flux outside the conductor is always zero. ‘57—— O g. chug gm E EIECtrlC “Eld lust DutSlde the surface is parallel to the surfacefﬁ W “ ((1313);; Css‘eclU c ..—5) E? (Tiléliﬁiclii is; The situation below pertains to the next two questions. A sphere of radiusa = 2.0 cm with a uniformly distributed charge 01 = 4.0 pC is at {hecehter bf a
conducting spherical shell of radii b = 4.0 cm and c = 5.0 cm that has a total charge Q2 =I e81} LLC. 18. Find the electric field at point A, which is at r= 1.0 cm from the center of the system. _.W m] 1_ __ we. r;  . C L O A. 1.2x107N/C Qdesiu‘gﬁ gVLLQJ + r L a. 2.2 x 107 MC IL
@45x107N/c 3 me E 3' __. _ r D. 5.7 x 107 N/C / M}
E. 6.9 x 107 MC “‘3 ' ﬂier “E 3 web , *mww— I; ,/ m fut an“
19' compare the Elecmc Potentials at points A, B, C and D_ 3 O \ 1 "WW—WWW“: \,
\ _____—_ —___._‘
.«j I I e; _ 9 _A. VA>VB>VC>VD ® VA>va=vcandvc<vo _ c 1/,e.>vﬂ=i/c>vD ' _.~
D. VA<VE=VEand VC<VD E. VA < V8: V: and Vc > VD  ' i ~— 4
 €  {wig} LE‘hS . . 3‘ if $154.. V nwsi‘ deu’ewac in ‘ /« 1V; 2]?
‘hﬁ—L E %I:E. \ > VS; m D D \‘jc’ 1‘ \r’ir: :7; $315; V : (“Emg ‘ U53 (ﬂ, C1” cm’h‘wu (15“) J f‘
x...“ v wt.
Lu 20. A point charge is placed near a neutral metal slabas shown beiow. @Q Which of the following is true? A. The slab acquires a net charge by induction, and exerts an attractive force on the point charge. The slab acquires a net charge by induction, and exerts a repulsiVE force on the point charge. The slab is polarized and exerts an attractive force on the point charge. The slab is polarized and exerts a repulsive force on the point charge.
E. Nothing happens because the metal slab is neutral to begin with. (’21 21. An infinite conducting slab with 8.85 nC/mz on each of the two surfaces is perpendicular to the x
axis and located between x = 0 and x = +1.0 crn' (i.e., the thickness of the slab is 1.0 cm). The V: 20 V
equipotential is atx = —1.0 cm. Find the potentiai at x = + 2.0 cm. A. —20v
5. —10v 20v
D. 30v
E. 50v 22. What is. the net capacitance between points A and B?
1.
l!) l: 0 lil: A. 1.0 pF 1 l i A
B. 2.4 F '1 r2 : P 125‘ E 1M: 2‘ J2 (Hoe—ex...”
i\ C 4‘2 LIF ; [ 1§_J_,_....a—\:d—MO
. .7 3 3
D" 8'3 “F ' 3.0 uF 2.0 ur
E. i
11 “F 2.0 [1F c,» e” 9“ “g” S “Lt"5197‘: '  H PL .1, l“, jl‘: +31:— l
1 :5 I?“ "‘ 23. Two spherical capacitors are connected as shown below: Battery Let Qiand V; U = 1, 2, 3, 4} be the charge and potential of each of the spherical surfaces indicated in. the
figure. Which ofthe following is trUe? A Q1 = 03 3 V2 < V3 I}; [YE {$31.2 Q1 = ‘03 I V2 = Va
(:C.J}Q]_=Q§;V4>V3
*n/ ! _.4—~'hu/v. D. Q1 = Q: ,' V4 : V1 pow—Mm"d—Fmi """"""""" WM “‘2. E. Q1=—QAJV1=V3
., a i— — it \il + 7; l'F
i Z 3 Dr q l {in \x’? > V13 Ll 1.5;. J 4» to 24. Two charges Q and —Q are located in a region of space, far from other charges, as shown below Consider the two imaginary spherical surfaces indicated with dotted lines in the figure. Which of the
following statements is correct? Spherez
a‘  — . _ _ hhﬁ“
2" ‘H‘
l \‘ I” Sphere 1 x I ,"‘“" X
'I (I x ‘
, I “ \
r " \ l I I m i ' Q l 5 Q
  ® I . ®
I “ I I
“ \ I, ’f \ ‘\ ,’ r \ \‘ a I \ \_____a’ l \ l ‘4 I
\ l
x I A. The electric flux through the larger sphere is larger than the flux through the smaller sphere
because the area is large r. ~:’_— i}; 515k“ O.i33'xr:~s’tj"i"_ (Asian l J . I
B. The electric flux through the larger sphere is smaller because it is closer to the negative charge, ', l
i. = “ .p. s m "T
which produces negative flux. l liners: Kati a — We c1..ﬂr;a.l.lr_e§ 1;} bit 0:12»; are. \,l c; The electric flux through both spheres is the same. t?“ I _ Gauss's law does not apply here because of the absence of symmetry. 'ér" [ﬂint3' 1M3"?
E. (The net flux through both surfaces is zero because the net charge is zero. c ’3'". 25. An insulating sphere with a uniformly distributed charge of 5.00 C has a radius of 1.00 m. A
concentric, thin walled metallic shell has a charge of 10.0 C and a radius of 3.00 m. What is the
electric potentiai of a point located 2.00 m from their shared center? Take V(°°) = 0 A. (10C)k/(2m)
B. (lsclk/(Brn)
c. (20C)k/(3.m)
p. (20C)k/(6m) .2 QED (35C)k/(6m) 26. The metallic object shown below has a negative charge. The points A and B are on surfaces ofthe
object that have spherical curvature with radii of 7.00 cm and 3.00 cm respectively. The magnitude
of the electric field. just to the left of point A is 21 N/C. The electric field just to the right of point B is: 9 N/C pointing to the right
9 WC pointing to the left
14 [WE pointing to the left
' . 49 MC pointing to the right Egjags‘d 49 MC pointing to the left 00.61? m an. '2:— q = 5.0 nC is placed in the middle of one of the sides (see figure), All charges have a mass of 1.0 g.
Charge q is released from rest from that position. What is the speed of charge q when it is very far from the square? A. 32 mm/s
B. 52 mm/s
C. 98 mm/s 110 mm/s 130 mm/s ...
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This note was uploaded on 02/11/2012 for the course PHYSICS 222 taught by Professor Ogilvie during the Fall '05 term at Iowa State.
 Fall '05
 Ogilvie

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