1051test1answersW11 - Circle instructor: Morrow or Yethiraj...

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Unformatted text preview: Circle instructor: Morrow or Yethiraj 1 Name: 50/- U no 4/; Lab period: Student Number: MEMORIAL UNIVERSITY OF NEWFOUNDLAND DEPARTMENT OF PHYSICS AND PHYSICAL OCEANOGRAPHY Physics 1051 Winter 2011 Term Test 1 February 11, 2011 —————-—-—-—_—________—___________ INSTRUCTIONS: 1. Do all questions. Marks are indicated in the left margin. Budget time accordingly. ix) Write your name and student number on each page. b) You may use a calculator. All other aids are prohibited. 4. Write answers neatly in space provided. Ifnecessary, continue onto the back of the page. U] DO not erase or use “whiteout” to correct answers. Draw a line neatly through material to be replaced and continue with correction. 6. Assume all information given is accurate to 3 significant figures. 7. Don‘t panic. If something isn’t clear, ASK! ———-——-—————-—___—______—_____ SEE LAST PAGE FOR SOME POTENTIALLY USEFUL FORMULAE AND CONSTANTS For office use only: _ l 1 2 3 4 total l Circle instructor: Morrow or Yethiraj 2 Name: Lab period: Student Number: [10] 1. A 0.4-kg mass attached to a spring is oscillating on a : ' _ I V horizontal frictionless surface. The maximum speed of i the mass is 0.275 m/s and its displacement from equilibrium can be written as x(t) : A c0s(a)l + ¢). (a) What is the total mechanical energy of the system? £5 imea : 1% (0.¢‘7)x60.;27f'}5)v : 0.0/5/ 1 (b) If the period of the oscillation is 0.6 5, what is its angular frequency? -gfl Ajzél/ff- /r -, IT @“w'g/é a S r M! “(/5 (c) What is the force constant of the spring? Kiwi/é: x Ie = W1 1 : 0m? Wow/4;) < tr}? 44,, (d)What is the amplitude of the motion? , 1 2 g- a. M .22.; fl 4 {99 :W 43.74%, (e) Assume that x(0) 2 O and that w (0) is negative. Find the phase constant and write an expression for x(t) in the form x(1) = A cos(a)t + gb). More a yawn—0 .: ¢.~ I 7;; ’14“): -—/,lv 5:4(wh0 «Alas/’44) <69 =9 51*4’70 lcfirfa X(;),0.0'252m c05(/0.5’t 15%) Circle instructor: Morrow or Yethiraj 3 Name: Lab period: Student Number: [10] 2. (a) A tube oflength L is open at one end and closed at the other. Its fundamental mode frequency is 256 Hz. Assume that the speed of sound in air is 343.2 m/s? (i) In the outline to the right, draw a diagram showing the nodes and antinodes for the ME /7‘ (D fundamental mode of this tube. Label the nodes w1th‘N and the antlnodes With A'. L (ii) Calculate the length ofthe tube. 3 2 I? 1.: A; 1):” ~-' A—‘Vgc :3".;_’:/.34m. @ 0'; L7/\ w" 4r (iii) Calculate the frequency for the mode represented in the diagram to the right. m 4—..__..______ _____’ )9 grit-“90.2397 roam. L $7222.23”: / 0:163M‘ (b) Two sources, labeled SI and 82, emit sound waves, in phase, with frequency 261 HZ. Assume the speed of sound in air is 343.2 m/s. (i) What is the wavelength of the sound waves? 7/: I) /\ -: A r Z o = 1W: 5 I. 3/ "I (ii) What is the phase difference in radians between the waves that arrive at the observer, from the two sources, when the observer is r1 = 25.0 mfrom source 81 and r, = 23.0 m from source 82? Aés’éAr : @rflg‘l‘rl) @ —; A?“ 3.17— x(2$7‘7' 33“) : 7.57 muffin-m5 (m. ' f‘f7mfl/M5)_ [NJ/"7 (iii) Now imagine that S; is located 25.0 m due west of an observer and that S; is located a distance Ar further west of S; as shown. What are the smallest and the second smallest values of Ar for which the waves from the two sources interfere destructiver at the observer? i ~.. AP: m Ap : Circle instructor: Morrow or Yethiraj 4 Name: Lab period: _ Student Number: [10] 3. A sinusoidal wave propagating along a very long string is described by the function y(xvf,) : A sin(kx + (of). (i) ls the wave propagating in the positive or negative x—direction? @ fle 7w/él'9'c 2/ 0p” a altar" ' (ii) The amplitude of the wave is 0.05 m and the maximum transverse speed of a point on the string is 2.10 m/s. What is the period of the wave? (Hint: First find the angular frequency.) 7/ : 4U asCéA. fk/f) 5‘ ‘/’V}WX/: ’4“) . ; .76th (9 ' w ’7?” if”: j; r:_/r 12.”: “Z” » 015/05 2‘ 4’ ’“"“2 (iii) The wavelength of the wave is 2.12 m. What is the speed of propagation for waves on this string? 7/: M a- A T @ —: 7/: Zi/gm. 0.xra; : MJ ’2. (iv) The linear density (mass per unit length) of the string is 0.075 kg/m. What is the tension in the string? @ 7; via :(/¢,/7$)1Xa.07ffij/»7 : /5‘.0 4/- (v) Now imagine waves of the same frequency traveling on a string at the same tension and made of the same material but having twice the diameter of the original string. What is the wavelength“? , _— : 77d? )tz/rfl; ,a/X; ’ otf,«/ Circle instructor: Morrow or Yethiraj 5 Name: Lab period: Student Number: [10] 4. (a) Two charges, + 3 uC and — 3 uC are located on the x axis of a coordinate system at x z «0.5 rn and x = +0.5 m respectively as shown. Point P is located on the y axis such that it is 1.25 m from each charge as shown. (i) What is the total electric field at point P due to the two charges on the x-axis. Give your answer in unit vector notation? J b7 [37 Symmt‘r/fi/ [7:0@ /‘ -5 " 5. ,m. x 3w a were (#2532); 74/ ? -6 =2x‘3’fimx0 3 wry/ac 0'97 @ (/Arq/Z— £297 : /. 33 m“ “4 A «:(‘*x g: Any/Hg c m (ii) What force would be exerted on a — 5 pC charge placed at point P? Give your answer in unit vector notation. J A 4 F: 35 ': «57/0 C “3”” @ *‘ “(fix/04M [A V 4 3% 4 (iii) If electric field lines were drawn to represent the electric field due to the + 3 uC and m 3 uC charges, would the field lines be more closely spaced at the origin (indicated by O) or at point P. Briefly justify your answer. 021/! /‘5 5‘;fflnit/‘ é/lL O Sl‘nCC 0 1'; c/05V _. 2L0 eayéx oéurje we? can/RAVE)“ /p @ fl'c/d’ /,«w.. @4541. Why? are [H fit Sameofl/‘I‘cfiéfi’d‘k. a: life/0V //‘ne§ arg Myra C/éfe/i 5/4c2flW/fl Mm 5/“ P. Circle instructor: Morrow or Yethiraj 6 Name: Lab period: Student Number: Some Potentially Useful Formulae and Constants: dzx * ~(02 r dtl ’ F! 2 k 511512 A! _ c 7.2 2 E, = ~kspnngx (Hooke‘s Law) E = kt, ll; _ 1 k 2 1 '2 r E — E .vprmgx +3177» E = kczig 7 27r , t t ’7 a) = ~f— (angular frequency) = 331 rn/s+0.6 1:1 >< TOC 7 ksprim: S. C a)“ = ’ ‘ m s » (DE = j E . dA 502 =% (DE : qlllSKlC i 60 (02 = In? Vzhg 27: r 2 —~ (angular wave number) ’1 q V = kCZ—L i 1‘, v = fl (wave speed) 4 sphere : :fl'r} T J v : W I” Asphel‘e : 47272 62y _ L 52y 8x2 v2 612 Physical constants: k ~~—L—*899><109N-m3/C3 “4%0 " " e=1.60x10""c 50 28.85x1043 CZ /N-m2 g =9.81m/S' ...
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This note was uploaded on 03/08/2012 for the course PHYSICS 1051 taught by Professor Michaelmorrow during the Winter '12 term at Memorial University.

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1051test1answersW11 - Circle instructor: Morrow or Yethiraj...

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