Young Modulus - Physics - Solved Paper, Exams of Physics

Download Young Modulus - Physics - Solved Paper and more Exams Physics in PDF only on Docsity! Pre wo Physics 124 - Analytical Physics ° SECOND COMMON HOUR EXAM Monday, Apr. 5, 2010 = a SIGN HERE NOW: The exam will last from 9:40 - 11:00 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, M.I.) enter your last name, then fill in the empiy 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 18 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 18 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 we 340 m/s, pair & 1.2 kg/m, Lotickorrodaboutend = (1/3)ml", and Ip = 1x10"? W/m?. 1. A 5 kg block is hung from a wire of radius 0.8 mm, cross sectional area 5x10-7 m?, length 2.2 m, and Young’s’ modulus 2x10!" Pa. How much does the wire stretch? Choose the closest answer. Hes 0 mn = F/A = foo _ Si W982 Din . Cb) tm 5 Y Ze/p., we ALE Se = > 2» Io" Pa * SHO as c) 2mm d) 3mm = e) 4mm 8,00 py, 2. The speed of a mass on a spring varies with time as v = 4 (m/s) sin(3t). The spring constant is 2 N/m. What is the total mechanical energy of the The ing? . mass on the spring’ Ars w Asin (ot) -= Ax 4 a) <0.27 oy b) in the range 0.2- 0.4 J =K+euatka = dy Zui a\e c) in the range 0.4 - 0.6 J E * 2 25¥( ° d) _in the range 0.6 - 0.8 J (6 nh Cy) cages 8. The figure shows the position (top), speed (middle), and acceleration (bot- tom) of a mass undergoing simple harmonic motion as a function of time. The four vertical bars indicate (from left) times 7), to, t3, and ty, respec tively (time increases as subscript increases), At which time is x > 0,v <0, and a > 0? t t ts t a) ty poor b) t x 6 EN oe oc) ts ab doe 7 ab doe t~ ' ' € one of them 4. A mass m on a spring of constant & undergoes simple harmonic motion of amplitude A. At what position is the speed of the mass half of its maximum speed? a) 2=0 aT =o Asinuot Wray = OA b) z= A/V2 . eo c) 2=A/2 Sin (ist) =e —> wt =Aresin 4, =30 os x= hen do’ = AS 14. Consider the picture shown of the traveling sound wave generated by a plunger. Which of the following statements is correct? a) The wave has different amplitudes at points P and Q. b) The wave has the same amplitude at points P and Q, but the oscilla- tions at the two points are 1/2 cycle out of phase. c) The wave has the same amplitude at points P and Q, and the oscilla- tions at the two points are in phase. d) The wave has the same amplitude at points P and Q, but the oscilla- tions at the two points Plunger oscillating are 1/4 cycle out of phase. in SHM e) The wave has the same amplitude at points P l and Q, but the oscilla- = “""") tions at the two points 4 are 1/8 cycle out of phase. 15. A 1000 Hz sound has intensity 1 mW/m?. How loud is the sound, in dB? It might help to know that Jy = 1x107?? W/m?. a) 100dB CacmaE) dB = Ze. \o* = = oe dB = (0d B fog a (odB bog o' = 40d & d) 70dB e) 60dB SANE. 16. The amplitude of a spherical sound sess drops by a factor of 3 when it travels from point A to point B. What is the ratio of the distance between the speaker and point B to the distance between the speaker and point A? a) This is a trick question - the amplitude is constant. b) 1/9 ¢) 1/38 As. Ya. L Me 2g ah ARS & 17. A police car with a 500 Hz siren is heading north on NJ turnpike at 35 m/s. You are heading south at 25 m/s. What frequency do you hear for the siren? Take the speed of sound in air to be 340 m/s. a) < 440 Hz ff TeV, Ar, = ~ 35% “TO b) 440 - 480 Hz 96% c) 480 - 520 He vi Ws a= 25% d) 520-560 Hz 2340425 = g 5 op WOH2E - sae Uy 18. What is the angle of a shock wave made by a plane traveling at 1.3 times the speed of sound? a) 38° = 0.66 radians oe Beles b) 44° = (1.3)7! radians Stuot We, ¢) 50° = 0.88 radians 75° = 1.3 radians woe = so” e) There is no shock wave at that speed,