UNIVERSITY OF SASKATCHEWAN Depatment of Physics and Engineeing Physics Physics 115.3 Physics and the Univese FINAL EXAMINATION Decembe 21, 2016 NAME: (Last) Please Pint (Given) Time: 3 hous STUDENT NO.: LECTURE SECTION (please check): 01 A. Zulkoskey 02 D. D. Janzen 03 B. Zulkoskey 04 D. S. Litt 97 D. A. Faahani C15 D. A. Faahani INSTRUCTIONS: 1. This is a closed book examination. 2. The test package includes a test pape (this document), a fomula sheet, and an OMR sheet. The test pape consists of 11 pages, including this cove page. It is the esponsibility of the student to check that the test pape is complete. 3. Only a basic scientific calculato (e.g. Texas Instuments TI-30X seies, Hewlett-Packad HP 10s o 30S) may be used. Gaphing o pogammable calculatos, o calculatos with communication capability, ae not allowed. 4. Ente you name and student numbe on the cove of the test pape and check the appopiate box fo you lectue section. Also ente you student numbe in the top ight-hand cone of each page of the test pape. 5. Ente you name and NSID on the OMR sheet. 6. The test pape, the fomula sheet and the OMR sheet must all be submitted. 7. None of the test mateials will be etuned. ONLY THE FIVE PART B QUESTIONS THAT YOU INDICATE WILL BE MARKED PLEASE INDICATE WHICH FIVE PART B QUESTIONS ARE TO BE MARKED QUESTION NUMBER TO BE MARKED MAXIMUM MARKS MARKS OBTAINED A1-25 25 B1 10 B2 10 B3 10 B4 10 B5 10 B6 10 TOTAL 75 Page 1 of 11
Decembe 21, 2016; Page 2 PART A FOR EACH OF THE FOLLOWING QUESTIONS IN PART A, ENTER THE MOST APPROPRIATE RESPONSE ON THE OMR SHEET. A1. Use the significant figues ules to popely expess the answe to the following addition poblem: 21.4 + 15 + 4.003 + 17.17 = (A) 57.573 (B) 57.57 (C) 57.6 (D) 58 (E) 60 A2. In lab M36, you studied the pefectly inelastic collision between a ball and a pendulum cage. Suppose that the mass of the ball was measued to be 65.6 ± 0.3 g and its speed befoe colliding was detemined to be 4.22 ± 0.25 m/s. Which one of the following expessions is coect fo the momentum of the ball befoe the collision? (A) 0.58 ± 0.55 kg.m/s (B) 0.277 ± 0.018 kg.m/s (C) 0.584 ± 0.072 kg.m/s (D) 0.277 ± 0.075 kg.m/s (E) 0.584 ± 0.036 kg.m/s A3. Two objects ae eleased fom est fom the same height at the edge of the top of a building. Object 1 is eleased fist, and one second late object 2 is eleased. Which one of the following statements is coect? (You may ignoe any effects due to ai esistance.) (A) Once both objects have been eleased, the distance between them emains the same as they fall, egadless of thei masses. (B) Once both objects have been eleased, the distance between them deceases as they fall, egadless of thei masses. (C) Once both objects have been eleased, the distance between them inceases as they fall, egadless of thei masses. (D) If object 2 is moe massive, then once both objects have been eleased the distance between them deceases as they fall. (E) If both objects have the same mass, then once both objects have been eleased the distance between them emains the same as they fall. A4. A wagon stats fom est and undegoes a constant acceleation fo 6 seconds duing tial 1. In tial 2, the wagon stats fom est and undegoes the same constant acceleation fo 2 seconds. How does the displacement duing tial 2 compae with the displacement duing tial 1? The tial 2 displacement is (A) one-ninth as lage. (B) one-thid as lage (C) thee times as lage. (D) nine times as lage. (E) 1 3 times as lage. A5. Two objects, of diffeent masses, m1 < m2, ae connected by a sting that passes ove a fictionless pulley whee a1 and a2 ae the magnitudes of the acceleations of the espective masses. Which one of the following mathematical statements accuately descibes the magnitude of the acceleation a2? (A) a2 < g (B) a2 > g (C) a2 = g (D) a2 < a1 (E) a2 > a1 A6. In the photo, a locomotive has boken though the wall of a tain station. Duing the collision, what can be said about the foce exeted by the locomotive on the wall? (A) The foce exeted by the locomotive on the wall was less than the foce exeted by the wall on the locomotive. (B) The foce exeted by the locomotive on the wall was the same in magnitude as the foce exeted by the wall on the locomotive. (C) The foce exeted by the locomotive on the wall was lage than the foce exeted by the wall on the locomotive. (D) The wall cannot be said to "exet" a foce; afte all, it boke. (E) Moe infomation e.g. about the tain s momentum and the stuctual integity of the wall is needed to answe this question. Page 2 of 11
Decembe 21, 2016; Page 3 A7. A ca of mass m tavelling at speed υ cashes into the ea of a tuck of mass 2m that is at est and in neutal at an intesection. If the collision is pefectly inelastic, what is the speed of the ca afte the collision? (A) υ (B) 21 υ (C) 31 υ (D) 2υ (E) zeo A8. Mak and David ae loading identical cement blocks onto David's pickup tuck. Mak lifts his block staight up fom the gound to the tuck, wheeas David slides his block up a amp on massless, fictionless olles. Which one of the following statements is tue? (A) Mak does moe wok than David. (B) David does moe wok than Mak. (C) Mak and David do the same amount of wok. (D) None of these statements is necessaily tue because the angle of the incline is unknown. (E) None of these statements is necessaily tue because the mass of one block is not given. A9. The gavitational foce exeted on an astonaut on Eath's suface is 650 N down. When she is in the Intenational Space Station, which one of the following statements is tue? (A) The gavitational foce on he is smalle. (B) The gavitational foce is exactly the same. (C) The gavitational foce on he is lage. (D) The gavitational foce on he is indeteminate: it depends on the space station's obital and otational speeds, which ae not given. (E) The gavitational foce is exactly zeo. A10. A satellite moves in a cicula obit at a constant speed aound Eath. Which one of the following statements is tue? (A) The satellite moves at constant speed and theefoe has no acceleation. (B) The satellite has an acceleation diected towad Eath. (C) The satellite has an acceleation diected away fom Eath. (D) No foce acts on the satellite. (E) Wok is done on the satellite by the foce of gavity. A11. The model shown to the ight consists of fou solid sphees, each of mass M and adius R, connected by ods of length L and negligible mass. This model is otating about the axis pependicula to the page though point O. What is the moment of inetia of the model? You may assume that R << L. (A) ½ ML 2 (B) ML 2 (C) 2ML 2 (D) 4ML 2 (E) 8ML 2 A12. Calculate the magnitude of the net toque on the wheel in the figue to the ight about the axle though O pependicula to the page, taking a = 7.00 cm and b = 16.0 cm. (A) 0.760 N m (B) 0.873 N m (C) 1.18 N m (D) 2.02 N m (E) 2.44 N m A13. One end of a cod is fixed and a small object with a mass m is attached to the othe end, whee it swings in a section of a vetical cicle of adius, as shown in the figue. At this instant, what is the tension in the sting? 2 2 mυ mυ (A) mg + (B) mg cosθ + (C) 2 2 mυ mυ (D) mg sinθ + (E) mg sinθ 2 mυ mg cosθ Page 3 of 11
Decembe 21, 2016; Page 4 A14. A box slides down a fictionless incline, and a hoop olls down anothe incline. Both inclines have the same height, and both the box and the hoop have the same mass. If both objects stat fom est, upon eaching the bottom of the incline which one will have the geate kinetic enegy and which one will have the geate speed? (A) The box will have the geate kinetic enegy and the geate speed. (B) The hoop will have the geate kinetic enegy and the geate speed. (C) Both will have the same kinetic enegy, but the box will have the geate speed. (D) Both will have the same kinetic enegy, but the hoop will have the geate speed. (E) The box will have geate kinetic enegy, but the hoop will have the geate speed. A15. A physics instucto, initially spinning on a stool with ams outstetched, pulls his ams in so that they ae close to his body. Which one of the following statements coectly descibes what happens when he pulls his ams towad his body? (A) His angula momentum inceases and he spins faste. (B) His angula momentum deceases and he spins faste. (C) His moment of inetia inceases and he spins faste. (D) His moment of inetia deceases and he spins faste. (E) His moment of inetia emains constant and he spins faste. A16. A wheel has a adius of 30.0 cm. How fa (path length) does a point on the cicumfeence tavel if the wheel is otated 4.50 evolutions. (A) 1.35 m (B) 1.41 m (C) 2.83 m (D) 4.24 m (E) 8.48 m A17. What is the angula speed, due to Eath's daily otation, of a peson living in Saskatoon (52.1 N latitude)? (A) 1.05 10 5 ad/s (B) 2.10 10 5 ad/s (C) 3.64 10 5 ad/s (D) 4.47 10 5 ad/s (E) 7.27 10 5 ad/s A18. What happens when a chaged insulato is placed nea an unchaged metallic object? (A) They epel each othe. (B) They attact each othe. (C) They may attact o epel each othe, depending on whethe the chage on the insulato is positive o negative. (D) They exet no electostatic foce on each othe. (E) The chaged insulato always spontaneously dischages. A19. A test chage of q (a negative test chage) is used to measue an electic field at a point P. The field is found to have a magnitude of 2 N/C. When the test chage is emoved, the electic field at point P (A) will be the same magnitude and diection as oiginally measued. (B) will change in magnitude but not diection. (C) will evese in diection with same magnitude. (D) will change both magnitude and diection. (E) will be zeo. A20. At a distance of fom a cetain positive point chage, the electic field ceated by the chage has a magnitude of EA and the electic potential due to the chage is VA. Which one of the following options is coect fo the magnitude of the electic field, EB, and the electic potential, VB, at a distance of /2 fom the chage? (A) EB = ¼ EA ; VB = ¼ VA (B) EB = ¼ EA ; VB = ½ VA (C) EB = 4EA ; VB = 4VA (D) EB = 4EA ; VB = 2VA (E) EB = 2EA ; VB = 4VA A21. An ideal, 12.0-V souce is connected acoss the seies combination of two esistos, R1 and R2. R1 = 4.0 Ω and R2 = 8.0 Ω. The cuent though R1 is (A) 3.0 A (B) 1.5 A (C) 1.0 A (D) 32 A (E) 4.5 A A22. An ideal, 12.0-V souce is connected acoss the paallel combination of two esistos, R1 and R2. R1 = 4.0 Ω and R2 = 8.0 Ω. The cuent though R1 is (A) 3.0 A (B) 1.5 A (C) 1.0 A (D) 32 A (E) 4.5 A Page 4 of 11
Decembe 21, 2016; Page 5 A23. You wish to use a negatively-chaged od to cause an isolated metal ball to acquie a net positive chage. Which one of the following pocedues will wok? (A) It is not possible to use a negatively-chaged od to cause an object to acquie a positive chage. (B) Connect the metal ball to gound, touch the od to the ball, then emove the od, and then disconnect the ball fom gound. (C) Connect the metal ball to gound, touch the od to the ball, then disconnect the ball fom gound, and then emove the od. (D) Connect the metal ball to gound, bing the od close to the ball but do not touch it, then disconnect the ball fom gound, and then emove the od. (E) Touch the od to the metal ball fo a few seconds, then emove it. A24. Ca batteies ae often ated in ampee-hous. This ating petains to the amount of a cetain physical quantity that the battey can supply. The physical quantity coesponding to the ampee-hou ating is (A) cuent (B) powe (C) enegy (D) chage (E) potential A25. A ball with a positive chage is dopped at the equato (whee the Eath s magnetic field is hoizontal and diected Noth). Immediately afte it is eleased, what is the diection of the magnetic foce acting on the ball? (image attibution: http://clipats.co/clipat/3775881) (A) East (B) West (C) Noth (D) Up (E) Down PART B ANSWER FIVE OF THE PART B QUESTIONS ON THE FOLLOWING PAGES AND INDICATE YOUR CHOICES ON THE COVER PAGE. FOR EACH OF YOUR CHOSEN PART B QUESTIONS ON THE FOLLOWING PAGES, GIVE THE COMPLETE SOLUTION AND ENTER THE FINAL ANSWERS IN THE BOXES PROVIDED. THE ANSWERS MUST CONTAIN THREE SIGNIFICANT FIGURES AND THE UNITS MUST BE GIVEN. SHOW AND EXPLAIN YOUR WORK NO CREDIT WILL BE GIVEN FOR ANSWERS ONLY. EQUATIONS NOT PROVIDED ON THE FORMULAE SHEET MUST BE DERIVED. USE THE BACK OF THE PREVIOUS PAGE FOR YOUR ROUGH WORK. Page 5 of 11
Decembe 21, 2016; Page 6 B1. A fish is attempting to jump to the top of a watefall that is 1.50 m high. The fish begins the jump (leaves the wate) a hoizontal distance of 1.00 m fom the base of the watefall. The fish jumps such that it just eaches the top of the watefall, that is, it is moving hoizontally when it eaches the top of the watefall. (a) Daw a diagam, showing the tajectoy of the fish fom when it leaves the wate until it eaches the top of the watefall, and you choice of coodinate system. (2 maks) 1.50 m 1.00 m (b) Calculate the vetical component of the initial velocity of the fish such that it just eaches the height of the watefall. (2 maks) (c) Calculate the time that it takes the fish to each the top of the watefall. If you did not obtain an answe fo (a), use a value of 5.50 m/s. (2 maks) (d) Calculate the angle of the initial velocity of the fish such that it just eaches the top of the watefall. If you did not obtain an answe fo (c), use a value of 0.550 s. (4 maks) Page 6 of 11
Decembe 21, 2016; Page 7 B2. A bullet of mass m = 4.20 g is fied paallel to an inclined table, into a wooden block of mass M = 255 g that initially sits at est. The bullet emains in the block afte the collision. The coefficient of kinetic fiction between the block and the table is 0.333, the angle of incline of the table is 30.0, and the bullet and block slide a distance of 0.425 m up the table befoe stopping. (a) On the diagam to the ight, daw the foces acting on the bullet/block combination afte the collision (while the combination is still moving up the incline). Include you coodinate system. (2 maks) (b) Calculate the wok done by gavity in binging the bullet/block combination to est. (2 maks) (c) Calculate the wok done by fiction in binging the bullet/block combination to est. (2 maks) (d) Calculate the speed of the bullet/block combination immediately afte the bullet has embedded in the block. If you did not obtain answes fo (b) and (c), use a value of 0.550 J fo (b) and a value of 0.300 J fo (c). (2 maks) (e) Calculate the initial speed of the bullet. If you did not obtain an answe fo (d), use a value of 2.50 m/s. (2 maks) Page 7 of 11
Decembe 21, 2016; Page 8 B3. A cicula disk of adius 16.0 cm is acceleated fom est to 1.26 10 3 pm (evolutions pe minute) in 3.00 s. (a) Calculate the aveage angula acceleation of the disk. (3 maks) (b) Assuming constant angula acceleation, calculate the numbe of evolutions of the disk duing the 3.00-s acceleation peiod. (3 maks) (c) A sample of blood in a small vial is attached to the im of the disk. The mass of a ed blood cell is 3.00 10 16 kg and the magnitude of the centipetal foce acting on it as it settles out of the blood plasma is desied to be 4.20 10 11 N. Calculate the new angula speed (in evolutions pe minute) at which the disk should be otated. (4 maks) Page 8 of 11
Decembe 21, 2016; Page 9 B4. A constant 18.0 N foce is applied to a cod wapped aound a pulley of mass M = 6.00 kg and adius R = 45.0 cm. The pulley acceleates unifomly fom est to an angula speed of 10.0 ev/s in 4.50 s. Thee is a constant fictional toque of τf = 1.60 N.m on the pulley due to fiction at the axle of the pulley. (a) Calculate the angula acceleation of the pulley. (3 maks) (b) Calculate the moment of inetia of the pulley. (The pulley is not a unifom solid disk.) If you did not obtain an answe fo (a), use a value of 12.5 ad/s 2. (4 maks) (c) The cod beaks at the instant that the pulley eaches an angula speed of 10.0 ev/s (at 4.50 s afte it began acceleating). Calculate the time fo the pulley to come to est. If you did not obtain an answe fo (b), use a value of 0.500 kg m 2. (3 maks) Page 9 of 11
Decembe 21, 2016; Page 10 B5. Thee chages ae aanged at the cones of an equilateal tiangle as shown in the figue. Conside a point P midway between the two chages on the x-axis. (a) On the diagam above, daw the diections of each of the electic fields ceated at point P by the chages. (3 maks) (b) Calculate the magnitude of the electic field at point P due to each chage. (3 maks) E (+8 µc): E (+3 µc): E ( 5 µc): (c) Calculate the magnitude of the net electic field at point P. If you did not obtain answes fo (b), use the following values: E (+8 µc) = 1.00 10 6 N/C; E (+3 µc) = 1.40 10 5 N/C; E ( 5 µc) = 7.00 10 5 N/C. (2 maks) (d) Calculate the diection of the net electic field at point P. Expess you answe as an angle with espect to the positive x-axis. (2 maks) Page 10 of 11
Decembe 21, 2016; Page 11 B6. Conside the mass spectomete shown in the figue. The electic field between the plates in the velocity selecto is 9.55 10 4 V/m, and the magnetic field in both the velocity selecto and the deflection chambe is 0.950 T. (a) Calculate the electic foce on a singly-chaged ion in the velocity selecto. (2 maks) (b) Calculate the equied speed of a singly-chaged ion in the velocity selecto such that the magnetic foce on it is equal and opposite to the electic foce calculated in (a). If you did not obtain an answe fo (a), use a value of 1.50 10 14 N. (2 maks) (c) Befoe enteing the velocity selecto, the singly-chaged ions must be acceleated fom est. If a singly-chaged ion has a mass of 2.18 10 26 kg, calculate the potential diffeence though which it must be acceleated fo it to acquie the speed calculated in (b). If you did not obtain an answe fo (b), use a value of 1.10 10 5 m/s. (3 maks) (d) Calculate the adius of the ion's path though the deflection chambe. (3 maks) END OF EXAMINATION Page 11 of 11