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Unformatted text preview: Exam A Semi om q 0(
go] blog 1. The displacement of a string carrying a sinusoidal traveling wave is given by
y(x, t) = (12.0 cm) cos“; III—1);? — (6.0 slm.
What is the speed of this wave? (a)1r/3m/s 'Comfan’hj gag/7: 120 CoSf—gx ’605] Wit/L (b) 6.017 / _' _ t  5:
6) 9.0/1rmmjs gaxltjq— (7m C05(K9L w ) ) an”, 18/1rm/s gim=/L.0)K=ﬂ/3Jw=6.o. F”!
(e) 36/1r m/s Usénj a): K v (chum; from, A=% ) 9m“. 6: BE vr)ﬁ% 2. A planet has half the mass of the Earth, and its radius is half the radius of the Earth.
Apprmcimately what will be the acceleration of a massive body dropped near the surface ofthis planet? _ _— m/VL '5’?! _) g (a) 5.0 m/s2 r” G R94 3 9 R1 " GNP/R: =(ﬂ)(ﬁ_€—)2’= amaze) 3.2:.236
«mm/s2 3e GMe/Ré m R“? z 00 9 _ m 3. A ball of mass m = 0.3 kg travels horizontally with a speed of 5.0 m/s and collides
elastically with a wall and bounces back with the same speed. If the collision with the
wall lasted for 0.05 s, the magnitude of the average force exerted on the ball in this collisionis: __
F; awrajcforcor 9—P = AKmv} 3mg“! (a) ION I At A 5 At ,,
(b)40N __.) F=0.3x[‘5.0~(—5’O)] :M550_) F=60N
@601“ . 005 0'05 (d) IOON _5_ m 1 m
(e) 120N bet“! 36,315 afterj 50 9/3 4. A top spinning on the ﬂoor precesses because the torque due to gravity, about the point
of contact of the top with the ﬂoor, causes the angular momentum of the top to change.
(b) parallel to the angular velocity vector The direction of this tor ue is:  * ""
q :er
(c) parallel to the axis of rotation T 3
(d) perpendimllartothe ﬂoor ,3 I /’ ff noneofthe above 73f?u£ f5 (7055 mducf‘b“ I, and F [Jenée/
. _ 9 2
Fer’oﬂnwcular to 50 th) ("6 Parallel to ﬂu floor 2 (a) parallel to the angular momentum 5. Apersonofmassm= 100kgisstandingonacartwithmassM =400kgwhichinitially
moves with velocity 10 m/ s on a track. At some moment, the person starts running with
velocity 5.0 m/s with respect to the cart’s ﬂoor towards the front of the cart (i.e., in the
same direction as the original motion). What is approadmately the velocity of the cart
now? (Hint: remember that the person's speed is measured with respect to the cart “ﬂab” Star‘s Mining) First com/ch the: Vela city Off/w, Person With
(a) 11 m/s “Spica; tow", Car) to one Alf“ {Upset to Hot flack: 90 “1/3 VFW“? 2 5+5 :15 m/s
(c) 7'0 “1/5 Now aﬂp/ Conjcrua h'on of mom/than! 30 écfm
(d) 5.0 m/s and after the F}: San staff: running .' r 5" r
(e) 10 “1/3 P (gifm) _ f/a/l’ef)—') (m +M) Via : m Vﬂr‘aﬂ‘f M V;
~—.> (100+ (foo) do = {00 #5 + 400 xvcal #7, V0“; 5000  1500 ._,
t if 40 o
6. A massive disk with rotational inertia I = 25 kgm2 is initially not rotating, but then a r; A
constant torque 1' = 5.0 Nm is applied continuously for 10 3. What is the magnitude of
the angular velocity of the disk at the end of the 10 s? (a)0'5md/s 6:16? —,s cx:§_.—_5'o:=0°2 56:4. (b)57rrad/s — —‘ ___. I .25 52.
(6)1.0rad/s wiwo+o<txwd50 —:w=0(f=0.2,2</0=2 (e) none of these 7. A playground merry—go—around has a radius R and a rotational inertia I. The merrygr»
around is spinning with angular velocity we and a child of mass m is standing at the
rim 3. distance R from the center (i.e., from the axis of rotation). When the child moves
to the center, the angular velocity of the merrygo—armmd is: (a) mo ﬂnj u/a/ momm item 15 Con 36er of, Mare/arc
2
93537331? at is m 8m lye/m and a/M ﬁt Chi/6’ “M
(d) wo/(I+m32) I 5" ﬂ" a“ f": "1
mm m’”, 910:;
(8) 5 / ll. :2 [Cd f z}. I g chi/J
._——,> [It:1 Xwo +Iwo=(MRz+I)wo anal ngwd+ A “(ﬂy501mm! F : J f/l‘ft In; 2 1
("m *1) “)0 = I“ —J M) — mom/€21: IJ/I 3 m Sin np'; Sing? 49ka 0 8. An object is dropped from an altitude of four Earth radii above Earth’s surface. If M is the mass of Earth and R is its radius, what is the speed of the object just before it
hits Earth? (Hint: Assume the Earth is a sphere. Also, notice that the object’s altitude
measured from the Earth’s surface is not the same as its distance from the center of the ﬂffpéz ConSert/afr‘or) 0/ 6'46ij bcf’wgm flag, painf;
4 m dic abo Vt, the act/#1 (cic 5 fadiifmm m sen/era/ (a) GM/R
2:; ﬁgs: t W) and the 5% a z m W m mm:
(331‘: f (d) m 59%: a W .) U{5R}+/(E(5K):U(K)Hame ~— " = "GmM .J_m 2— FLm ii : I
2 5R 7?— +1 I/ > 2 l/ EGEM 1V . A ladder which weights 400 N is leaning against a wall. The length of the ladder is 5.0 In, and the center of mass of the ladder is at its center. The base of the ladder
is 3.0 m from the wall. Assuming that the wallladder contact is frictionless, what is
magnitude of the force of the wall on the ladder? (Note: the ladder is stationary, since there is friction at the ladderﬂoor contact.) NC t t a 6 t Faint 0
Or?u65 0“ must Sum to Zcrof (b) 200N A a H
(c) 250N 50m Z €=0 *3 ‘ij 1 deu:o
(d)300N :5: g o_m Kr Sm H: 3,, She:
(e)400N {Sine 5 o 40m 3 "17 (F wan waq ' 0
C 392.3» __  _ .. .
° "5"“ " Qua” — 400x§ x o 6
FM 6 OL_Y_J ; SK”,
.. r 3m" ‘7) Pam” ‘1 {SON
9» qu ‘ elm 10. An object of mass m = 2.0 kg, oscillating on the end of a spring with spring constant k = 32 N/m, has amplitude A = 0.5 m. Its maximum speed is about: 2.0m/s U=2LK9tl ,KEsELml/Z,E =U+K£ {at
(b)3'0m/s — b i=1 =79 KE:0 U=_.L 3,! 2.
(0)4.0111/5 W m "t 2 / 2 KIM§—x3.2xa.5_4J (d) 5.0 m/s r.) Etoé : 4+ 0 = 4 I (e) 6.0m/s __ when 1:0 (e?m/féﬂ'um fem/J) (1:0, K51: Kfmax:
6&0}: 0+ K5 =4ﬁ K5,“, =§LmV2 =J—xlxv r A! ,.., $4.,
max " max ‘2 f” 1 V: 2
max_ 5 —"1 4 11. A tuning fork produces sound waves of wavelength A in air. This sound is used to cause
resonance in an air column in a pipe, which is open at both ends. The length of the pipe CANNOT be: For 0: Pipe of least/3 L’opgn af Ends, firSZ‘
(a) M2 fwd Sfandinﬂ wan mm“ arc;
(b) A (d) 3/2 3 . . g (e) 5A 2
/ , 33. [5 mt an: 0/5/24
432% L52)! 4 Si‘mdinf wauemm. 12. AWmemiumdﬁthaﬁeqmyofIMHz. Anohanukming
whathiImvithapeddlmm/u. Iftheofmndiuwm/n, the charm hum sand with a freqmncy of about:
(3) won Hz Mix» Ma observer is mom/my, ﬂu farm: /a (lama: F0, Damp/"IS Shari is: @600st (awn. ’ ;; (,_ ﬂypﬂgg; 13.0}: s 0.5mm Mama. .4 340
_ 4 x
"  ' f = 600 Hz 13. A‘rhlockofmaM=mkgmu‘themda£uﬁgidunibrmhudlungﬂthdthe
sm‘mnnMrseﬂkg. IfthnbthnttheMntL/Alﬁmthcmm
thM'mmmmmanhwummmdm‘M?
(Eat:,th§masofthenniﬁrmhiruhouﬂnotbeignme¢'lhbg=Him/ﬂ) 0N (b) ION
(c) mN«
(d) 3011
(e) 40N Ntf fanfare: about t 'PoinfO ('5 Zero if {76: 60! is fo 4 remain hoh'ianfc/ ' A:  d d .= — '
Z: 0 atF+C ﬁrmso )szr..4 609x2r1:_500 x‘Tt:=o l. 14. A pulley (which can be considered to be a solid uniform cylinder) with mass M = 60 kg
is suspended from the A rope passes over it with a 20.0 kg block attached to
one end and a 30.0 kg block attached to the other. The rope does not slip on the pulley.
When the speed of the heavier block is 1.0 m/s, what is the total kinetic energy of the
pulley and blocks? (Hint: The radius of the pulley is not speciﬁed because it is not
needed. For the pulley, K = éIwz; both I and w depend on the radius R of the pulley ‘ cha a 113' '
msu wyt tit 03110813011” To fa/K’hbf,‘c elm/97 0F :3": Pufk/ and 5/6me Co» 5;; f! of
(c) 60J (wig=2!— tfdﬂJ/afr‘ona/ Kinetic 6003
((1) SI” [41' Mfuﬂcr R2 0,5 1‘41 blooé 5 0M flu, l
(6) 120.1 .2 IV In to h‘onalb'rmﬂc Mtrﬂ 0% ﬂ" Pot/def; 601‘}! 6/ock5 [MW 5/9“d I“?! bat“ 2 . 2, ,
KEtof — ~2LMV 4 2LMV +‘—2sz1,%—20.0,( l.OZ+‘2L30OKOL+—%v6(2 R2('L)Z
) ' . = [045415—140 aw ‘3 R 15. At the same instant that a 1.0 kg ball is dropped from 50 m above Earth, a second ball
with a mass of 2.0 kg is thrown straight upward from Earth’s surface with an initial speed of 10 m/s. They move along nearby lines and may pass each other without colliding. At
the d of 2.0 s, the height above Earth’s surface of the center of mass of the twoball system is about (in your calculations use 9 = 10 m/s2): To Fi‘hd t/r Cenfa'of mas! af {=20 5/ H’Icﬂosiﬁ‘?” 0% 10’“ Edd/h ball af [Lari05 /:5 “fa/rle f
C 5f ' 15" '75’ 75f 2' 2' F— 75:30
" 7’ WI 9* s; w. biz/525550432 =30 )1 m d 2 d . d “ 2nd
H 6m 2” ball. 7’1" gaud+gzndt+légtis0+{OK2—5sZZ:O—)CL :0 nt 15% 4
50M :M y + Nlndz 1" : I0x30+30X0 ——,> 36M: IO m
M 1 +M2n lOiJaO 16. A 50 N weight is hung from two ropes as shown. The tension in the horizontal rope has n 61
approximately the magnitude of: j, New to” ; 5 2 ((3 L Ma) L7! 7. and)! detach0M
91 c 87N  Zj Fy=O—A TSFHBO—SO '30
(d)115N #sT’:SS_03 =100N
(e) 54N Horizontalmpe EF 1 ”‘ °l I :0 g) C 3 “T :1
T513130 50A] K __ T as o O 9 T = [00039 30 =8?N a ...
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This note was uploaded on 12/02/2009 for the course PHY 317k taught by Professor Kopp during the Spring '07 term at University of Texas.
 Spring '07
 KOPP
 Physics

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