midterm 07

midterm 07 - 73 Final Exam (Barwick) Winter ’07 (Do not...

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Unformatted text preview: 73 Final Exam (Barwick) Winter ’07 (Do not open until instructed) Name 6b\uihie’v\ StudentlD MC Ans (A,B ,C,D,E,F) mm: 601” Some rules before beginning: 1. Make sure that your name, ID number, and discussion info is printed on this cover. 2. You are allowed a simple calculator (see the list of allowed calculators in the syllabus) and 2 sides of 8.5 x 11 inch page of paper for notes. This test contains several blank sheets of paper to work out the problems. You may only write in your exam. 3. You may not copy from your neighbor, nor consult or communicate with any person during the exam. Please report any instances of academic dishonesty to myself (via email or in person). Please be as specific as possible. 4. There are Multiple Choice and Free Response questions on this exam. No Partial credit will be assigned for the Multiple Choice. Partial credit will be assigned for the free response, but only if there is an absence of wrong statements, equations, etc. Write neatly. I must be able to follow your logic to assign partial credit. Messy work will be graded harshly. 5. For the multi-part problems: We will do our best not to double penalize you for mistakes in the previous parts. Also, some parts are independent of other parts so read the problem carefully. 6. If you do not understand the questions, make sure you ask to clarify the problem. When in doubt, it never hurts to ask. 7. Please show student ‘ID or drivers license when we go around and spot check. 8. For Free Response: ll 0X ALL YOUR ANSWERS and STATE THE UNITS - correct answer for units may be worth a '0th 0r tw 9. For Multiple Choice: Transfer all of your answers to the from or we will not grade your answers. 10. Use the blank sheets to answer the Free Response questions. Do not try to cram all your answers on one page. Clearly indicate the part of the problem that your are answering (a, b, c, d, etc.). If we cannot figure this out easily, we may grade incorrectly. 11. For free response, symbolic answers are usually worth most of the points (unless it is trivial or given to you). If there are numbers given in the problem, then simply substituting them in for the symbols is often satisfactory. You can leave answers in terms of irrational numbers so don’t bother with a calculator unless you have time to spare at the end. You should include units if numbers are given though. The maximum score for this midterm is 90 pts. There are 7 MC questions and all questions are worth 5 pts, but not all require the same amount of time to answer. Scan the exam and do the easier problems first. There are 3 free response problems worth 55 pts. This midterm is worth 30% of your grade for this class. You have 1 hour and 20 minutes to complete the questions. I repeat, scan the exam and do the easier problems first. MULTIPLE CHOICE (only one answer is correct — Make sure to transfer your answer to each question to the front of the exam. ) All MC questions are worth 5 pts. 1.) A ball is suspended by a string that is tied to a fixed point above a wooden block standing on end. The ball is pulled back as shown in the figure and then released. Consider two cases: A) The ball rebounds elastically from the block B) Double sided sticky tape causes the ball to stick to the block \, Which statement is true a) The ball for case B is more likely to knock the block over No b) Both cases will produce the same impulse on the block M“? c) The temperature increase in the block is larger for case A N0 (1) It is not possible to say which case is more likely to knock over the block / _ / g/ (/ because it deends on mass of ball and length of string “#0 , .4 A m mam» M» Atoms W “M: Sc east ’4' Safes MW FA’C; ' ff con/Sim 2). Three linear sticks of different material are placed in an oven. The 1-», me, T’lu,‘ S (.4117 graph shows length as a function of time in the oven. Assume that the 0:56 A. is W. _ oven induces the same time rate of change of temperature for all 3 7a” MEL ML, , materials. Note that slopes A and C are the same. Rank the coefficient of linear expansion, a, for each material, largest first. a) CLA>OLB>QC b) GC>QB>CLA c) OtB>ClA>GC L i C - c I: —— i 5" $2. the t if at" a ‘I hit OM F'" n K (a. (Baht/1 \ _ LA<LC§0 ' i at $0535; . ta 3843C t MAMKC' new! ‘ - Cd 32> > o( . . . . . . C- 3.) A cylinder contains n moles of an ideal gas w1th known 7/. if the gas is mampulated a adiabatically, what is the work, W, in terms of the given initial quantities Pi, Vi and fin 6" C) W = (Pivi-P VQ/(Y-l) F' " La, ' I d) w: 'Pi(Vf'\;i) W 7‘ w 1 k 6) none of the previous statements are correct [,3' ’Y 4). The figure on right shows two identical sticks with the same mass, M, and length (= 2L) attached by a hinge. Initially one stick is hanging down at a right angle. It is then rotated so that both sticks form a straight line. What is the distance between the center of mass of the first configuration and the straight configuration? a) L b 2L d) L e) none of the previous answers is correct 4 Jr ' "- A “L ( far/l ) @mn + mo >1 : .3 a - kinds; eat ahead 4 5) Look at the figure on I' - rig . e magnitude of the force exerted in the x direction varies ‘ function of time. It acts on a 3 kg particle. Find the impulse on the particle. a) 25k*m/ d WW k r W- WW a c) 6 kg*m/s d) 4 kg*m}s e) none of the previous answers is corre Whig: z (5): ti?é ‘ S 3 , Catt. I J 6) Refer to the previous problem. If the initial velocity of the particle, Vi: 0, What is the final A it .4 A velocity? a) 12 m/s b) 6 m/s lc) 4 m/s l d) 4/3 m/s e) none of the previous answers is correct 7) Refer to the previous two problems. If the initial velocity of the particle was vi = —2 m/s (i.e, it was initially traveling in the —x direction) , What is the final velocity of the particle? b) 4 m/s (1) the final velocity must be negative e none of the previous answers IS correct I Problem 1: (10 pts) Jeopardy Please write a problem whose solution is given by the equation below. (1/2)(0.006kg)(300 m/s)2 + (1/2)(0.003 kg)(600 m/s)2 = (0.009 kg)(128 J/kgC)(327 C — 22 C)+ (0.009 kg)(2.45x104 J!kg)+(0.009 kg)(128 J/kgcxn n 327 C) Describe the system, and include the necessary information to produce this equation. For example, does the problem assume no energy transfer? What about the forces, if any, need to be specified? Make sure to state what is wanted. Hint: you obtained a solution similar to the one above in the hOmework problems. @140 E5 Le Vf’rnmg Two 5 Cure) 7Qng ML, (9% M5 Sew WW W: (UT: 300ml; pf: (:00 Wk Dfl 4% 132an inm 353M- @ (Qt-FILM ~13: w Memdig be wee Aw Wtfiw (g {18 33/ij “Cm, A:% (7% Mid! may kin/“X; f'WS/ Moi 74mm in: JYSMOir/kj ) m DJ 6% W7 Mai TWM a WM ‘ Misc/Mo f5 3.2200 Mat WAw/Wf'm¢’5 35”? {’t 8 no Wk. E Problem 2: (20 pts) First Law of Thermodynamics W “‘1 Look at the P-V diagram. The change in internal energy along the central path from A to C is +800]. The work done along 9 path ABC is —500 J. AVG _ AFN”: n-l'S’OOJ: V a) (5 pt) Is energy removed or added as the system is manipulated along path A_liC. How much energy is transferred by heat? Hint: Is the change in internal energy dfierent along ABC and directly between AC? 6 C. H B C It 8 L + W e . . mst Cf Ag“ [gas “[(d/{Ql/t +0 5 5%,, I 5 QWC: AEffC'Fh/MC: @3093”) -' (#5003) 1’ l“ "or ‘93 had b) (5 pt) If PA=5PC, what is the work, WCD, going from C to D? Hint: You are given the work along ABC, which is the same as work along AB. The work along CD is simply related to the work along AB, so once you know the work along AB, you can figure it out for CD. wk new; WM} thaw. no mam m5 sue, fitf Fen Cens‘l' Prague , W} PAV MK Angz-fl Kb row” way-11mg; é wan) 23165003) - c) (5 pt) _ " ' a IS the energy exc nge With the surroundings, QCDA, by heat along pa CDA? Hint: Use first law of thermodynamics. You should recognize that WCDAzWCD, and you found WCD in part 19. Does the ma nitnde of the change in internal energy between point A and C depend on path? / WC“? W5 ‘ ' r- s r- - 00J Q We I‘m (Pa/Li" Sa p - roblem continues on next .1- CKan 1 “3003—” (WWW) : d) (5 pt) If the chan e in internal energy in going from point D to A is +500J, how much energy must be transferred along paffi C to 5? Is the transfer of energy to the system or away from the system? Hint: Use First Law of Thermodynamics on path CD. You can determine the change of internal energy along path CD by subtracting the change along path D- A fi'om the beaten change between A and C (and reversing the sign since the system is now going from point C to A ). The work along CD was found in part b. p‘DA A];th _—. +5005 ; AErrt+AIEIHiA I {—fl amen, Spam :3 ' {even/Yap mm drag/{1cm ti {‘6’fo Wave? 149 #174; gm»; _, b5 g a); ___ C {DA g0 “AEAC 7'AElnibf; :1) AEi-Mr :‘At*- «re—r‘W‘fiDfJD: (mi) Ql§0°5> 61’ - > :. —/‘lOOJ-:Q (90 = 412% “Good”? = (*'30°T)-(’°” i all 9; 99 mm am Mr 65am a heat flesh/c i ifl‘ g Problem 3 (25 points): A tennis ball of mass 0.05 kg is held just above a basketball of 0.5 kg. With their centers vertically aligned, both are released from rest at the same moment, to fall through a distance of 1.25 m. Assume that the basketball falls slightly faster than the tennis ball (since it is slightly denser) and 1335111 strikes the ground elastically, reverses direction, and then collides elastically with . the tennis ball. Assume all the motion [W occurs along the vertical axis. We wish to A find found out why the tennis ball reaches a greater height than compared to the case of just dropping 'it by itself from the same h'h. elgt Vaduz, a) (2 pt) Find the velocity of the basketball, vb, just before it strikes the ground. Him: The velocity ofthe basketball just before it strikes the ground is vb = (ngffl. Use g: 10 m/szfor the acceleration due to gravity. XL (U) 3 (95> 0i ) 2 (Q = ‘ “ 4 Dive 68 " b) ( pt If the collision etween e basketball and the ground is elastic, w at is the velocity magnitude and direction (where +y is up) of the basketball ter collision. * 1 y 1‘ east; Get/151w; freng (cmseweaj flaw Heap 9’“ . _, r .. _ vb ‘H’us coup. LS who Imam EA’L . .50 xiii” I m c) (6 pt) Now consider the collision between the basket all and tennis ball. The magnitude of the velocity of the tennis ball is very close to the same value as the one you calculated for the basketball in part (a) (because it fell the same distance). Write down the conservation of momentum equations before and after the collision for the y-coordinate, using the notation 111b, vbi= mass and initial velocity of basketball, mp vLi = mass and initial velocity of tennis ball. Use VM and vIf for final velocity of basketball and tennis ball. Once you have written the equation symbolically, then put the values in the equation that you kno . 'Tlu,._il;g{C/m3: cam is @NW 5M0”. with; 5W dLSW/ magi/u a W [amt Mam/'96 is '9‘ Mom; at: ‘ Va :— 5“ «gm: d)(5 pt) Write the conservation of energy before and after the collision between the basketball and tennis ball. Once again, the notation, mb, vbi= mass and initial velocity of basketball, mt, vti = mass and initial velocity of tennis ball. Use VM and vtf for final velocity of basketball and tennis ball. Once you have written the equation symbolically, then put the values in the equation that you know. gmbvb’fignvgfl {nVJF+§/¢gf (6M4; M; é (0,5’)($)1+(0iosl(5)¢ r; a: 12",, + (9,0;- ygf “‘87 e) (10 pt) Use equations in pans (c) and (d) to determine the final velocity of the tennis ball, vtf. How high does it go? Based on the class demo, does your answer for the height make sense? Hint: you may find the quadratic equation useful: cul+bx+c=0, then x=(~b:Vb2—4ac)/2a 7/ Hm Quays/LN; (r11 Iowa‘s C. M Wdfl Sgt/trims 6? gym,“ 1);, Maw. amt 1g; , Many/4, apt/WW; 45,2 $0.0]? 29,25 ’63.??2’f fl . {call in demo dial met [ Bounce as Mala £0150 Cellisws he?” £14575 . ...
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This note was uploaded on 06/26/2008 for the course PHYS 1 taught by Professor Barwick during the Spring '08 term at UC Irvine.

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midterm 07 - 73 Final Exam (Barwick) Winter ’07 (Do not...

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