Translational Speed - Physics - Solved Paper, Exams of Physics

Download Translational Speed - Physics - Solved Paper and more Exams Physics in PDF only on Docsity! Poe Physics 124 - Analytical Physics FINAL EXAM Tuesday, May. 11, 2010 So buttons = Ie SIGN HERE NOW: The exam will last from 4:00 - 7:00 P.M. Use a #2 pencil to make entries on the answer sheet. Enter ID information items 2-5, now, on the answer sheet before the exam starts... In the section labeled NAME (Last, First, MI.) enter your last name, then fill in the empty circle for a blank, then enter your first name, another blank, and finally your middle initial. Under STUDENT # enter your 9-digit RUID Number. Enter 124 under COURSE; you may ignore the section number. Under CODE enter the exam code given above. During the exam, you may use pencils, a calculator, and one 8.5 x 11 inch sheet (both sides) with formulas and notes. There are 30 multiple-choice questions on the exam. For each question, mark only one answer on the answer sheet, There is no deduction of points for an incorrect answer, so even if you cannot work out the answer to a question, you should make an educated guess. At the end of the exam, hand in the answer sheet and this SIGNED cover page. Retain the exam questions attached for future reference and study. ‘When you are asked to open the exam, make sure that your copy contains all 30 questions. Raise your hand if this is not the case, and a proctor will help you. Also raise your hand during the exam if you have a question. Please have your student ID ready to show to the proctor during the exam. Possibly useful information: at the earth’s surface g = 9.8 m/s”, Usoundinair m4 340 m/s, pair ¥ 1.2 kg/m, Isotidaisk = (1/2)mr*, and Ip = 1x10-? W/m. 1. A-solid disk rolls down a 45° slope, starting from rest. What is its trans- lational mee when it has gone 5 m along the slope? wah = mes STs bw $f mrt fio’ = 3 ah = omer" ore \Agh _ (424805 4 S SG a) <2m/s “ w b) 2-4m/s 6.8 = c) 4-6 m/s Cay" 68s) e) >8 m/s 2. An object is stationary, in equilibrium, in a uniform gravitational field. Which of the following is true? a) The object must_be symmetric — it can be a circle, but not a wrench, hy" It is possible for there to be three external forces acting on the object. c) Each force on the object must be balanced by a single equal force in the opposite direction. d) All forces must point at the center of mass so that there is no net torque on the object. e) The sum of the torques is zero because the sum of the forces is zero. (They are not independent conditions.) 3. A 2m wire of negligible mass consists of two 1-m segments, one of steel (Young’s modulus = 2 x 10!! Pa) and one of brass (Young’s modulus = 1x 10" Pa). The cross sectional area of the brass segment is four times larger than that of the steel segment. When a weight W is hung from the ceiling by this wire, the steel segment stretches by 1 mm. Find the elongation of the brass segment. a) 0.25 mm y = TA om i AG Y _ 4642 ce) Imm ft, — = 3 tam NY = Fz, Yo an! “8p vA 2 A t= AL Ab, 10. 11. 12. 13. Your friend speaks to you with an intensity of 65 dB, measured 1 m from your friend. You can hear sounds as quiet as 5 dB. How far away can you be and still hear your friend? Assume a spherical wave. a) 6m b) 60m 1 50/10 c} 120m fam =10 7, = 1000» = 1000 d e) 3600 m While you are standing still, a police car with a 400 Hz siren passes you, going 40 m/s. What is the magnitude of the change in the frequency of the siren that you hear from when the police car is approaching to when it is moving away from you? The {peed of sound in pe is 344 m/s. CED f-p2e they abide, bel ie i= fo aay aa mM; TV, o Spy ~ Sosane | AE 400s | 2 2A .| = Gh Bue e) 47 Hz \ (“s fey. The lowest frequency a person can hear is about 20 Hz. How long should an organ pipe, open at both ends, be so that it produces a 20 Hz sound as its fundamental frequency? Use v = 344 m/s. v vw a) 344m = Led ~2.- b) 172m 7 Te 5 A 2b Ce) 88m) - ©. B44 _ 2.4 ad) 4.3m 2¢ D im e) 215m A piano tuner stretches a steel piano wire with a tension of 765 N. The steel wire has a length of 1.5 m and a mass of 0.01 kg. What is the frequency of the string’s fundamental mode of vibration (first harmonic)? a) 37 Hz a = Odi ka, wt avez \E p pr Lom 27 c) 236 Hz d) 314Hz f.% = Vix x 2) 578 Hz A 24 14. Two adjacent organ pipes, open at one end and closed at the other, are played at the same time, One is 3.3 m long and the other 3.4 m long. The speed of sound in air is 344 m/s. What is the beat frequency between the fundamental frequencies of the two pipes? b) 1.5 Hz voy 1. 1 c) 3.1 He Ii Af =0.25v LL =0.25x344m/sx Jam 34m =0.77 Hz a) 51 Hz 1 . , e) 100 Hz 15. ‘The dimensions of thermal conductivity # are: a i mK b) W/(mK c) W/(m?K) d) Jm/K e) Wm/K 16. A cube of aluminum, with linear coefficient of thermal expansion a = 2.5 x 10-5 K-?, is heated so its temperature is increased by 40 K. By what fraction does its volume expand? AN = BLA) = 25x10 3440 =0.003 b) 10-8 ce) (1/3) x 1073 d) 10-9 e) Not enough information is given to solve the problem. 17. One spring day in NJ the numerical value of the temperature in Fahrenheit was 50 more than the numerical value of the temperature in Celsius, What was the temperature in Fahrenheit that day? Choose the closest answer given below. = 2 F\= a) 40°F Te) = iGs 32 a Tr) ex b) 50°F < ~42e c) 60°F = fy- \ S y%& GEIeE) y- So =(¥- 32) 3 e) 80°F 18. 19. 20. 21. How much energy is needed to convert 1 kg of ice at 0°C into 1 kg of water at 20°C? It might help to know that the latent heat of fusion of water is 334000 J/kg and the specific heat of water is 4190 J/(kg-K). Q=mbeweat = b) 334 kJ 3 c) 250 kJ = [%33hxto® + (*4,2 *1D% 20 = d) 84kd s e) 4kJ = ANB ID What is the net heat emitted radiatively by a person of body temperar ture 37°C on a 25°C day? Assume the person has surface area 2 m? and emissivity 0.5. It might help to know the Stefan-Boltzmann constant is o = 5.67 x 10-8 W/(m?-K4). a) 0.09 W Qe eraearG (4-1!) = b)_ 0.11 W 3 4 3“\ 771W ) 77 W. =pe , “> { Blo - 24 = a) oe W =o ¥2¥571H10% ( 2 e) 525 W What is the volume of 2.5 moles of an ideal gas at a pressure of 50 kPa and a temperature of 20°C? a) 0.008 m3 nRT 2,5 %B.3 ¥ 293 % er = ARYL ee tee Pe xO. b) 0.12 m3 N P Bx tod (2m ec) 8m? d) 120 m3 e) 305000 m$ Consider two perfectly rigid containers. The first container holds n moles of hydrogen (Hz), while the second container has the same number of moles of neon (Ne). If it takes 100 J of heat to increase the temperature of the hydrogen by 3K, by how many degrees will the same amount of heat raise the temperature of the neon? a) 1K b) 2K | ch 5 c) 3K Q=nChar = nC’ ar™ AT’ = eur Ar 53K =5K d) 4K