UNIVERSITY OF SASKATCHEWAN Department of Physics and Engineering Physics

Transcription

1 UNIVERSITY O SASKATCHEWAN Department of Pysics and Engineering Pysics Pysics MIDTERM EXAM Regular Sitting NAME: (Last) Please Print (Given) Time: 90 minutes STUDENT NO.: LECTURE SECTION (please ceck): 01 Mr. Adam Zulkoskey 0 Mr. Brian Zulkoskey INSTRUCTIONS: 1. Tis is a closed book exam.. Te test package includes a test paper (tis document), an exam booklet, a formula seet, a scratc card and an OMR seet. Te test paper consists of 8 pages, including tis cover page. It is te responsibility of te student to ceck tat te test paper is complete. 3. Only a basic scientific calculator (e.g. Texas Instruments TI-30X series, Hewlett-Packard HP 10s or 30S) may be used. Graping or programmable calculators, or calculators wit communication capability, are not allowed. 4. Enter your name and student number on te cover of te test paper and ceck te appropriate box for your lecture section. Also enter your name on te exam booklet and scratc card. 5. Enter your name and NSID on te OMR seet. 6. Te test paper, te exam booklet, te formula seet, te scratc card, and te OMR seet must all be submitted. 7. No test materials will be returned. QUESTION NUMBER MAXIMUM MARKS MARKS OBTAINED A1-1 1 B1-4 8 B5-8 8 B9-1 8 B MARK out of 36: Page 1 of 8

2 PART A OR EACH O THE OLLOWING QUESTIONS IN PART A, ENTER THE MOST APPROPRIATE RESPONSE ON THE OMR SHEET. A1. A U-tube is partially filled wit water. Mercury (wic does not mix wit water) is ten added to te rigt side of te tube. Te top of te mercury is a distance 1 above te level of te interface between te mercury and water. On te left side of te tube te top of te water is a distance above te level of te mercury-water interface on te rigt side. Wat is te density of mercury,, in terms of te density of water, w? (A) (D) 1 = w (B) 1 = w 1 (E) = w (C) 1 = w = w A. Two solid objects of identical mass are placed in a container tat is filled wit an unknown liquid. One object floats and te oter sinks to te bottom. Wic one of te following is a true statement concerning te volumes of te objects? (A) Bot objects ave te same volume. (B) Te floating object's volume is greater tan te volume of te object tat sinks. (C) Te floating object's volume is less tan te volume of te object tat sinks. (D) Noting can be said about te volumes witout knowing te densities of te objects. (E) Noting can be said about te volumes witout knowing te density of te unknown liquid. A3. A pipe as a section wit a diameter of 1.0 cm, followed by a section wit a diameter of 4.0 cm. How is te flow speed of an ideal fluid troug te 4.0-cm section, υ4, related to te flow speed troug te 1.0-cm section, υ1? (A) υ4 = 1 16 υ1 (B) υ4 = 1 4 υ1 (C) υ4 = 1 υ1 (D) υ4 = 4υ1 (E) υ4 = 16υ1 A4. Wic one of te following quantities is at maximum magnitude wen an object in simple armonic motion is at its maximum displacement? (A) acceleration (B) speed (C) momentum (D) kinetic energy (E) frequency Page of 8

3 A5. A rectangular block as dimensions, l, and w, as sown in te diagram below. If a force of magnitude is applied parallel to te top surface of te block, wic one of te following expressions is correct for te sear stress exerted on te top surface of te block? l w (A) (B) w (C) w (D) (E) w A6. Due to a build-up of sludge, te effective radius of a orizontal oil pipeline becomes alf te original radius. To compensate for tis reduced radius, te pipeline operator increases te pressure difference across te lengt of te pipeline by a factor of four. If Q1 is te original volume flow rate troug te pipeline, wat is te new volume flow rate, Q, in terms of Q1? You may assume tat te viscosity of te oil does not cange. (A) Q = 4 Q1 (B) Q = Q1 (C) Q = Q1 (D) Q = ½ Q1 (E) Q = ¼ Q1 A7. If one could transport a simple pendulum of constant lengt from te Eart s surface to te Moon s, were te acceleration due to gravity is one-sixt (1/6) of tat on Eart, by wat factor would te pendulum frequency be canged? (A) fm 6fE (B) fm.5fe (C) fm 0.41fE (D) fm 0.17fE (E) fm = 3.5fE A8. Wic one of te following pairs of quantities do you need to know in order to calculate te wavelengt of a travelling wave? (A) frequency and period (B) speed and amplitude (C) amplitude and frequency (D) frequency and speed (E) period and amplitude A9. Te speed of a wave in a stretced string is initially 50 m/s. Wat will be te new wave speed if te tension in te string is increased by 18%? (A) 50 m/s (B) 54 m/s (C) 1 m/s (D) 59 m/s (E) 45 m/s Page 3 of 8

4 A10. How is te direction of propagation of an electromagnetic wave oriented relative to te directions of te associated electric and magnetic fields? (A) parallel to te magnetic field, perpendicular to te electric field (B) perpendicular to te magnetic field, parallel to te electric field (C) perpendicular to te magnetic field, perpendicular to te electric field (D) parallel to te magnetic field, parallel to te electric field (E) parallel to te magnetic field, anti-parallel to te electric field A11. It is observed tat te air in a pipe resonates at frequencies of 10 Hz (te fundamental) and 600 Hz, and possibly oter frequencies between tese two values. If te pipe is open at bot ends, ow many additional resonant frequencies are tere between 10 Hz and 600 Hz; and if te pipe is open at one end and closed at te oter, ow many additional resonant frequencies are tere between 10 Hz and 600 Hz? (A) open: 3 ; closed: 1 (B) open: 1 ; closed: 3 (C) open: ; closed: 0 (D) open: 0 ; closed: (E) open: 5 ; closed: 1 A1. If te tension in a guitar string is increased by a factor of 3, by wat factor does te fundamental frequency at wic te string vibrates cange? (A) 9 (B) 3 (C) 3 (D) 1 3 (E) 1 3 PART B WORK OUT THE ANSWERS TO THE OLLOWING PART B QUESTIONS. WHEN YOU HAVE AN ANSWER THAT IS ONE O THE OPTIONS AND ARE CONIDENT THAT YOUR METHOD IS CORRECT, SCRATCH THAT OPTION ON THE SCRATCH CARD. I YOU REVEAL A STAR ON THE SCRATCH CARD THEN YOUR ANSWER IS CORRECT (ULL MARKS, /). I YOU DO NOT REVEAL A STAR WITH YOUR IRST SCRATCH, TRY TO IND THE ERROR IN YOUR SOLUTION. I YOU REVEAL A STAR WITH YOUR SECOND SCRATCH, YOU RECEIVE HAL-MARKS (1/). I YOU STILL DO NOT HAVE THE CORRECT ANSWER, BUT REWORK YOUR SOLUTION AND REVEAL A STAR WITH YOUR THIRD SCRATCH, THEN YOU RECEIVE 0./. REVEALING THE STAR WITH YOUR OURTH OR ITH SCRATCHES DOES NOT EARN YOU ANY MARKS, BUT IT DOES GIVE YOU THE CORRECT ANSWER. YOU MAY ANSWER ALL OUR PART B QUESTION GROUPINGS (1-4, 5-8, 9-1, AND 13-16) AND YOU WILL RECEIVE THE MARKS OR YOUR BEST 3 GROUPINGS. USE THE PROVIDED EXAM BOOKLET OR YOUR ROUGH WORK. Page 4 of 8

5 Water moves troug te pipe sown below in steady, ideal flow. At te lower point sown in te figure, te flow speed is.16 m/s and te pipe radius is.50 cm. At te iger point located at y =.50 m, te pressure is Pa and te pipe radius is 1.30 cm. B1. Wic one of te following pairs of principles/equations applies to te flow situation described above? (A) Te Continuity Equation and Poiseuille's Law (B) Poiseuille's Law and Bernoulli's Principle (C) Te Continuity Equation and Bernoulli's Principle (D) Te Continuity Equation and Stoke's Law (E) Stoke's Law and Poiseuille's Law B. Wic one of te following statements is correct concerning te pressure and flow speed in region compared to region 1? (A) Te pressure is lower in region but te flow speed is iger in region. (B) Bot te pressure and flow speed are lower in region tan in region 1. (C) Bot te pressure and flow speed are iger in region tan in region 1. (D) Te pressure is iger in region but te flow speed is lower in region 1. (E) Te pressure is lower in region tan in region 1 but te flow speed is te same. B3. Calculate te volume flow rate in te upper section of te pipe. B4. Calculate te pressure in te lower section of te pipe. Page 5 of 8

6 B5. A tensile force stretces a wire of original lengt L by an amount L. Consider anoter wire of te same composition and tickness as te first wire, but of lengt L. If a force of is applied to tis wire of lengt L, ten te amount tat it stretces is (A) ¼ L (B) ½ L (C) L (D) L (E) 4 L Te following 3 questions deal wit steel cables of cross-sectional area 4.00 cm and unstressed lengt 5.0 m. Te elastic limit of steel is Pa and its Young's modulus is Pa. B6. A single steel cable is used in te lifting mecanism of an elevator. Calculate te amount tat te cable stretces wen a stationary object (a loaded elevator car) of mass kg is ung from te cable. B7. Calculate te maximum upward acceleration tat te elevator car can ave before te stress on te cable exceeds te elastic limit. B8. You decide tat you want to increase te limit on te maximum upward acceleration to a value of 6.00 m/s by attacing more tan one cable to te elevator car. Calculate te minimum number of cables required so tat te upward acceleration is 6.00 m/s and te stress on eac cable does not exceed te elastic limit. Eac cable experiences te same stress. Page 6 of 8

7 B9. A speaker designed to emit sperical sound waves is producing a sound intensity of 8 W/m at a distance of 1 m from te speaker. Wat would be te intensity of tis sound at a distance of m from te speaker? A sound wave from te siren on Ambulance 1 as an intensity of W/m at a certain location, and, at te same location, a second sound wave from te siren on Ambulance as an intensity level tat is 13 db less tan te sound from Ambulance 1. B10. Calculate te intensity level of te sound wave due to te siren on Ambulance. B11. Calculate te intensity of te sound due to te siren on Ambulance. B1. If te location of interest is 50.0 m from Ambulance, and assuming sperical wave fronts, calculate te average power output of te siren on Ambulance. Page 7 of 8

8 B13. Two tuning forks sounding togeter result in a beat frequency of 4.00 Hz. If te frequency of one of te forks is 58 Hz, wat is te frequency of te oter? Two train wistles emit identical frequencies of sound of 177 Hz. Wen one train is at rest at te station and te oter is moving nearby, a commuter standing on te station platform ears beats wit a frequency of 6.00 beats/s wen te wistles are blowing at te same time. B14. If te temperature is 35.0 C, calculate te speed of sound. B15. Sound waves are longitudinal waves wit alternating sections of compression and rarefaction. Calculate te distance between consecutive sections of compression for te sound wave emitted by te stationary train. B16. Tere are two possible speeds tat te moving train can ave. Calculate te speed of te train tat corresponds to te commuter on te platform earing a frequency of 183 Hz for te sound from te moving train s wistle. END O EXAMINATION Page 8 of 8