{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

exam 3 key fall 08 - Physics 1710 Fall 2008 Examination...

Info icon This preview shows pages 1–16. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 10
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 12
Image of page 13

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 14
Image of page 15

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 16
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Physics 1710 Fall 2008 Examination 3 .‘*1Na1fie: LL T _KEY—A— Student ID: . irIn‘structor(circlesone); , ,0 ,VKobe‘é, . ,Lukic—Zniic ' Weathers This test consists of 8 multiple—choice questions and 4 free—response problems, for a total ,, ofllO points ‘(so that 10 points of extra credit are possible). To receive credit for the free-response problems, you must show all of your work on the pages provided. Don’t hand in any extra sheets or other paper. You may also earn partial credit for the some of the multiple choice problems if you show your work. Suggested procedure for solving the problems: 1. > Read each problem carefully and make sure you know what IS being asked ' ' before starting the problem. ~ Draw a figure for the problem. ' List the parameters given. Write down the equations to be used. Solve for the answer symbolically. Substitute numbers into you final equation and circle your answer. aweaw* WORK THE EASY PROBLEMS FIRST” 1. (7 points) What fraction of the period does it take for a simple harmonic oscillator (e. g., a pendulum undergoing small oscillations) to go from maximum displacement to a displacement at which its potential and kinetic energies are equal? 1:; ii? W'AWO‘WSSWaf/gfinfl win/re w= K =>k=w2m c) 1/4 Displacement K ('0sz ng mi {:0 (Wd’sfl) C2? iiis ”that a: imam ?0(:W)fiax Wm: Marina 2%” HM =2mu2 => :me/iaswt zwazm/ismawt => Coswt = swat or ”€th =( :1: gr ifflwg if . 2. (7 points) A particle located at the position vector f = (4-.00i + 5.005) III has a force .. A A N i = (2.00i + 3.00 j)Aacting on it. The torque about the origin is @Eiiifim i J k 4 5 . .m M a c) (—2k)N-m =4.“ 5.« 2n 3“ k- (4mm numb ZN-mk d) (—5k)N - m 2” SN e) (2i+3j)N - m 3. (7 points) Two disks of identical mass but different radii (r and 21') are spinning about the same axis on frictionless bearings and at the same angular speed coo, but in opposite directions. Initially, they are not touching; then the disks are brought slowly together. The resulting frictional force between the surfaces eventually brings them to a common angular velocity. What is the magnitude of the final angular speed, 60f, in terms of coo? a) COf=COO/4 ‘3’ u b) COf=2600/5 _ J c) _a;f=5wo/9 @ .COf=3a)0/5 ‘13:, e) (Of: 600 | 1’ Baku. A“?! Use Wmafmaa’ulatmmwim‘ Ibefafq " Inna “ [rug * Izruo = Ur" Ilr)°’¥ .. 1 V, 21-1 “3.9?" 4-l 3 g. u; a 12.:- Ion : 2W1(2r amrwb .. ”w = .. (0o lzrtL émarY+fimrt 4+1 6 5 4. (7 points) A piano's middle C string vibrates at its fundamental frequency of 261 .6 Hz. On one piano the total mass of the string is 0.0100 kg and the length of the string is 64.0 cm. What is the tension in the string? Recall that 1/2 wavelength fits on the string for the fundamental vibration. PMLté ”w'd’l 11:1; = 2L"? a) 9.8N ._.. b) 122N <:>"7 wal U;f; => 2146:]; c) 385N : , 1 4 . ‘ 2. :4vuLl‘z = 4 cola;- 0.64... (26145"); =|7§Z N 5. "‘(6 points) You are standing between two speakers. The speaker on the left IS emitting a tone with frequency 306 Hz. The speaker on the right 18 emitting a tone with frequency 295 Hz. Irritated by the beats, you try to eliminate them by Doppler shiftng the frequencies so you hear them as the same. The speed of sound is 343 m/s. In which direction would you have to run to eliminate the beats? a) left, towards the speaker with 306 Hz b) right, towards the speaker with 295 Hz 6 strai ht ahead I You M +11 move. so W the higkw di not nz2:0“? at all i: {(2%) is shifted (W Go (Mama 19m 306 He Sam) M SOWW {W as 501‘}fo h'WGO’ W5 2959(250wm / ., nil) r (W 306th ° 295M: 2%: 6. (7 points) Standing 5.00 in from a jackhammer in operation, the sound level is llOfidB. How far away from the jackhammer would you have to be for the sound level to be at 70 dB? Treat the jackhammer as a point source. a) 45m. f . Iy-v b) 50 m ‘ q “0115‘ [010% T: (3 388m 0" Wism‘a-‘é m r *1 ‘0 i . A: L I d) 50km 40d3' |0(]%_-10% °)=I0iefifi=l0ifi f3. 9%" 42—40%:9 ~ '$ ,04. .r, 1741'? -(gy I2 War: r. $ :I-_ .. [02 '>- (‘HOOVX I =I00'5M 3 500m 7. (6 points) Kepler’s 2nd law states that «a line drawn from the Sun to a planet will sweep . out equal areas in equal times. This law follows from a) conservation of energy. b) conservation of linear momentum. @ conservation of angular momentum. , ) the nonzero torque exerted on the planet by the Sun. e) the l/r2 nature of the gravitational force. I Remtlder‘wwim‘ m , , .5. a ‘ _. 4 - rx A é __ -‘ a L 1‘ dr dA-élrxdrt-glr voltl => 3.? élrwi;$filr”m‘7l‘fi finals MAILSO exertsmforinmapw'aual Iowa. 32 :f:o =3>~li=cauw ~“ d—é:(‘m'&ant 8. (7 points) A solid sphere of mass M and radius R is released from rest on an inclined plane with an angle of 6 . What is the smallest value of #5 needed to ensure that it rolls without slipping? ‘ a) tanB b) (2/5)sin6 (1/5)cose (2/7)tan6 e) (Mg/R)sm9 ZS Sphere. Pivots about cwlncl POM 1’ when r! rolls wdfiml‘ dipping . so 273?: IP“' IP2 R “ ~ $> masme ~=R (3&th “119% => 0, = -— ggs'me ' N Shallow ‘ 2ij .ma‘ =>. ”sue 4‘ we. a» f: wgsynélwa m: gwn Wu“ we Mwewéwee e/us: $1M 9. (14 points) A uniform solid cylinder of radius R = 0.100 m and mass M = 5.00 kg is supported on a frictionless axle at the top of a ramp that makes an angle of 0 = 30° to the horizontal, as shown in the figure. A cord of negligible mass is wrapped around ci1cumference of the cylinder, and the free end IS attached to a block of mass m - 2. 00 kg that slides without friction on the ramp. The cord does not stretch. a) Find the acceleration of the block down the ramp when it is released from rest. . b) Find the tension in the cord. . ‘1‘‘ N P g .1 l2. 1:. a: Add NeWiIIM M (an! foam block' 252‘ -WLO.,, ._ ‘> wussme —T= ma, (1) 12.15221242222192224224122212 22312221222 21,1 1.2 => T1251“ ~sz ‘12 '-;4>;"T=gMa (z) Solve (|)aMd(2)§w 0. MT' , , . p ‘ 3'3 98151/53 5m3o° EV ‘- :2 ’SMG =’ W 311 =,.-—-————-—-———— =2J3m a. ”l “"1““ =1“ “MT “LN; 22.. . 2. 922.22., ,- ; b)T— 1311104? 551:3 218mg: I 10. (14 points) A student stands on the center of a rotating platform that has frictionless bearings. He has a 2. 00 kg object 1n each hand, held 1. 00 m from the axis of rotation of the system. Assume that the moment of Inertia of the platform + student remains constant at 1.00 kg-m 2. The system is initially rotating at 10.0 rpm. Determine a) the initial angular velocity in radians per second, b) the angular velocity of the system in radians per second after the objects are brought to a distance of 0.200 m from the axis of rotation, and c) the change in the rotational kinetic energy of the system as the objects are pulled closer to the center of rotation. left—4 ->' rd:— 1- ‘ 2 J" ,_ I‘ ‘1} g y I- '_ 2: . 4-, a ma. Iiw;:I‘wa $ w¥=w;.fi=wi‘M1;IO$‘@ W/ LL22 0 z, n m L » lWl‘s“? ”21$an c)4§Kr‘;'il<¢-K4= gig. 41144: :3—4 5[(;§W+zmq)n (1Wt2m2)w] flats“ 422159 42..) X4554) (H44 422440») )0 ml 1! II 11. (14 points) A spaceship of mass In: 5.00 X 104 kg moves around a planet 1n a circular orbit with a period of T= 3.00 hours at a distance of 122.00 X105 m from the planet’ 3 center a) Find the mass of the planet. b) Find the kinetic energy K of the spaceship. c) The spaceship’s engines are fired briefly (so that the distance the spaceship moves away from the planet while they’re on is negligible). What minimum additional kinetic energy AK must the spaceship’s engines impart to the spaceship for it to escape from the planet? , ,- 7:, . r;- - 4&3; ‘ 47(2R3 ~ 4112 (ZXIQTMf r . . , 2 - W.” . a) WTPTK’T’T’M“ T EMT T‘“ “ T T M 6T1 saltwater-3%? b) Emil?“ Swiefltle' [I E=é . 111103 GT?“ ‘7 (22% W V‘= o.= R kr‘clrwlm‘ orlax‘t have. u = ,W cm GMM' = 6-67YIOT'N‘K‘431'4-WTOITE3‘5‘10T5 2Kn—T 2K Z-anotm =- C) To escaea’fiw Spaccétarl‘tls 15050} E? W W lMi WW'EO EI~ O'- ‘ . ”e- K'Tz‘v“ ZR E": ETAK- O =E>AK= E=%’%—Ti3.39xww§' (I a other wardsfffm. Line‘ficw affix: shtp mud IN. douMwL) 12. (14 points) A mass m = 3.00 kg is suspended by a vertical spring, and is displaced downward a distance d = 5.00 cm from its equilibrium position before being released from rest at t = 0. When it passes through its equilibrium position, it is observed to have speed v = 7.00 m/s. a) Find the spring constant k of the spring. b) Find the period Tof oscillation. c) Write an expression that gives the distance of the mass f1 om its equ111b11um position at any time t > 0. .. , L , é)/iffh€£flMt ibfimrwmmaadf‘fle 515%»: is [(012110 dimmdokfw, ,. ' , afléifijwzis 1%,;th ”Winklemw' sW,so ~ -4 30 05M); ”$231“ AF ’3‘ 5:8,WNAN=--(w=F=14om¢mA) e) y= Ashtédtw whu A=at ml y(f~o)=~'al=>- 4:43.34; 339-42: 3 y. com 57414611147, t it) a was... 095(l40mJ/5 t) Physics 1710 Fall 2008 Examination 3 Name: KEY B (See KEY A —For detailed 501mm) Student ID: Instructor (circle one): Kobe Lukic-Zrnic Weathers This test consists of 8 multiple—choice questions and 4 free-response problems, for a total of 110 points (so that 10 points of extra credit are possible). To receive credit for the free—response problems, you must Show all of your work on the pages provided. Don’t hand in any extra sheets or other paper. You may also earn partial credit for the some of the multiple choice problems if you show your work. Suggested procedure for solving the problems: 1. Read each problem carefully and make sure you know What is being asked / i , before starting the problem. Draw a figure for the problem. List the parameters given. Write down the equations to be used. Solve for the answer symbolically. Substitute numbers into you final equation and circle your answer. aweww WORK THE EASY PROBLEMS FIRST” . ,vs..,dm_..4.us._m. . . ..... ..... .. .. .. . . l. (6 points) You are standing between two speakers. The speaker on the left is emitting a tone with frequency 306 Hz. The speakeron the right is emitting atone with frequency 295 Hz. Irritated by the beats, you try to eliminate them by Doppler shifting the frequencies so you hear them as the same. The speed of sound is 343 m/s. In which direction would you have to run to eliminate the beats? & .» a)-~ straightahead r’ - r ' b) not move at all @ right, towards the speaker with 295 Hz (1) left, towards the speaker with 306 Hz 2. (7 points) A piano's middle C string vibrates at its fundamental frequency of 261.6 Hz. On one piano the total mass of the string is 0.0100 kg and the length of the string is64.0 cm. What is the tension in the string? Recall that 1A; wavelength fits on the string for the fundamental vibration. @ 1752N‘ b) 980N c) 385N d) 122N e) 9.8N 3. (7 points) Standing 5.00 m from a jackhammer in operation, the sound level is 110 dB. How far away from the jackhammer would you have to be for the sound level to be at 70 dB? Treat the jackhammer as a point source. a) 50 m 4. (7 points) A solid sphere of mass M and radius R is released from rest on an inclined plane with an angle of 6 .’ What is the smallest value of ,us needed to ensure that it rolls Without slipping? ' a) (2/ 5)sin6 b) (1/5)cosG @ (2/7)tane d) tanB e) (Mg/R)[email protected] 5. (6 points) Kepler’s 2nd law states that a line drawn from the Sun to a planet will sweep out equal areas in equal times. This law follows from a) the nonzero torque exerted on the planet by the Sun. b) conservation of energy. 0) conservation of linear momentum. @ conservation of angular momentum. e) the l/r2 nature of the gravitational force. 6. (7 points) What fraction of the period does it take for a simple harmonic oscillator (e.g., a pendulum undergoing small oscillations) to go from maximum displacement to a displacement at which its potential and kinetic energies are equal? a) 1/16 (E) 1/8 c) 1/4 d) 1/3 e) 1/2 7. (7 points) A particle located at the position vector i" = (4.00i + 5.00;) m has a force F = (2.00i + 3.003) acting on it. The torque about the origin is a) (5k)N-m b) (—2k)N-m @ (2k)N - m d) (—5k)N'm e) (2i+3j)N'm 8. (7 points) Two disks of identical mass but different radii (r and Zr) are spinning about the same axis on frictionless bearings and at the same angular speed am, but in opposite directions. Initially, they are not touching; then the disks are brought slowly together. The resulting frictional force between the surfaces eventually brings them to a common angular velocity. What is the magnitude of the final angular speed, 60f; in terms of am? a 60f: coo / 4 ® wf= 3 £00 / 5 c) 60f: 5 coo / 9 d) 60f: 2 £00 / 5 e) CUf= €00 9. (14 points) A uniform solid cylinder of radius R = 0.100 m and mass M = 4.00 kg is supported on a frictionless axle at the top of a ramp that makes an angle of 6 = 30° to the horizontal, as shown in the figure. A cord of negligible mass is wrapped around circumference of the cylinder, and the free end is attached to a block of mass m = 3.00 kg that slides without friction on the ramp. The cord does not stretch. a) Find the acceleration of the block down the ramp when it is released from rest. b) Find the tension in the cord. _ 5M0 , ollc'ir/sf :mSOD' _ . y b) T: film: 541.3. 2.54%; = 10. (14 points) A student stands on the center of a rotating platform that has frictionless bearings. He has a 3. 00 kg object in each hand, held 1. 00 m from the axis of rotation of the system. Assume that the moment of 1nertia of the platform + student remains constant at 1.00 kg-mz. The system is initially rotating at 12.0 rpm. Determine a) the initial angular velocity 1n radians per second, b) the angular velocity of the system in radians per second after the objects are brought to a distance of 0.200 m from the axis of rotation, and c) the change in the rotational kinetic energy of the system as the objects are pulled closer to the center of rotation. a1». 12% em 17,—; ms =m I ZWGa “+23 (ilk) 1:, w w-w: (26ml M— J . ) ‘ IWwZM / lav-“+23% (714‘ C)AK “HUWQWM; (15w +ZW‘)w.] [(1W123H(Zm)allm4/) (“saw 423%{1M\)(I.26w#)] ' ll. (14 points) A spaceship of mass m —- 6.00 X 104 kg moves around a planet 1n a circular orbit with a period of T: 4.00 hours at a distance of R 2.00 ><106 m from the planet’s center. a) Find the mass of the planet. b) Find the kinetic energy K of the spaceship. c) The spaceship’s engines are fired briefly (so that the distance the spaceship moves away from the planet while they’re on is negligible). What minimum additional kinetic energy AK must the spaceship’s engines impart to the spaceship for it to escape from the planet? 4“ R3 (2.106“ 3 GT‘ Zinnia; (it 36% MK _ GM“: 667xlo“N-a£1-228i103 (W 04%; " ' 2- 2mm 12. (14 points) A mass 'm = 4.00 kg is suspended by a vertical spring, and is displaced downward a distance d = 3.00 Cm from its equilibrium position before being released from rest at z‘ = 0. When it passes through its equilibrium position, it is observed to have speed v = 7.00 m/s. a) Find the spring constant k of the spring. b) Find the period T of oscillation. c) Write an expression that gives the distance of the mass from its equilibrium position at any time t > 0. am ":72— 4%?- OM b) "2“"2“F,aom m an [Tow/s) =Asin[w+*€P) = o 03m'5m(233ml/5 t 1g): —- 003m 605(233raJ/s t) ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern