Exam1Solutions

Exam1Solutions - 1[3.5...

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Unformatted text preview: 1. [3.5 points] [Exam #32] _____________________________________————-—————- An airline passenger carries a plumb bob (a string with a weight attached to one end) on her trip. When she holds the string so that the weight hangs freely, she notes that the weight hangs vertically. From this she can conclude that the plane is moving at a constant speed. False True [KL O‘F ’RFOM [3.5p0ints] ’HNL \jfll’ ‘l’l'Qa/Q .196 FMOJ‘CM +0 «HAL (Lou/{aroJ-{avt . ____________________________—.__.————--————————— 2. [3.5 points] [Exam #32] Consider a wedge that rests on a horizontal table as shown in the figure below. A block is placed onto the wedge as shown. There is no friction between the wedge and the table, and there is also no friction between the block and the wedge. In this case the wedge will be accelerated to the right. A. True False [3.5 points] 0N3 “mi e. fl N NEW $(>Q\v~’~"w< WWQQ‘ onabloob DX' W00, 0’“ blOC/k’ £0( ()1/ W admddiwu Fij wedfib _______________________________.__———————————- 3. [3.5 points] [Exam #32] ______________________________.__.—————————-— Consider a wedge that rests on a horizontal table as shown in the figure below and assume there is no friction between the wedge and the table. A force is now applied vertically as shown in the figure. This force will cause the wedge to move to the left. Frictionless table OMWFMN [3.5p0ints] . ‘ "To dfigelgr‘L-fe- [A +l/UL. horn' M2 0“ WM“ M quSi’ be & OTC/L M flu Mntdmhqa Plow/Le, 4. [3.5 points] [Exam #32] Abullet is fired from a rifle with a speed v0 at an angle 3 with respect to the horizontal axis (see figure below) from 21 011E that is a height 11 above the ground below. The speed of the bullet when it strikes the ground depends on the value of e. @False B. True V I ’ 1 a. I [3.5poz'nts] { V‘FX +ij Ngl : V5<C1636)L4 vigl'mef +9814 c0516 + sin'le = 1 WM: b3ng W No Q‘s NYE. 5. [3.5 points] [Exam #32] Consider a string hanging from a ceiling. The tension at the top of the string is less than the tension at the bottom of the string. flake B“ True ‘ 7°? «N vodjhi at Jm gin-n ‘ __________ agm mm 4mm} WW? WI.“ 'S’rfihg [3.5points] Se m Mass 9.? +INL 5+)“ 3 IS “of Mflhaublbn bottam 1.0? / +of Msmcdl 03 Mlmflwg ow +ms‘on Mm, [MS +0 Suppori' W’Yj (IHL micsth {WI ergl'ovm Me, has to LL odple, +0 5MP i’lms AM “HAIL WSS- “MM I so fiat, > {bottom 6. [3.5 points] [Exam #32] When passengers ride roller coasters, they often report funny feelings in their abdomen. This arises because, when you pass through a valley in the track, your apparent weight is smaller than it is when you stand on the ground“ B. True. . [3.5p0ints] + N<—~lws is w mm" W NUT/6' Q. 2F = 9% 2 WW} N _ MW- in bottom «>15 M WW; [3 armor ‘l’hom «pl/um ELMO“? 04,1 +M jromd. 7. [3.5 points] [Exam #32] After winning a baseball game, one player drops a glove, while another tosses a glove into the air. The acceleration of the glove going down is larger than the acceleration of the glove going up. A. True _ » Fl \/ 8. [3.5 points] [Exam #32] A flatbed railcar is moving at a slow but constant velocity. A man stands in the railcar, facing sideways (perpendicular) to the motion of the railcar. The man holds a baseball at arm's length and drops it onto the railcar bed. The principle of inertia predicts that the ball will land slightly behind the drop point on therailcar. A. False TIM/H'ch tells us “ti/WE objeei‘, all/£910“? . True I. ll“ malfitm-W 0~S ijl‘ I'S erofanl . (pill awh'm ale/mg {is m SW. W ‘l 90%. S‘W’Xce. “HAM/z, {5 W0 Fora, lt/\ ‘ ' ' i vww'aami‘oi OliVLC/i‘im ,+m harn'%ov\t‘c~€ cmPowwt VF Jag woe/{m will not Cal/kw <70 . I . . Happens Refumceficw I 2W” . Rodi cow“ :' Q ;., Gtrwgoi @ij‘.. 9. [3.5 points] [Exam #32] If an object is acted on by two finite constant forces, it is possible for the object to move at constant velocity? \w B. False F, F. [3.5poz'nts] *3 b: A éF : f F1 : CD So 7—? ® ______________________________._____—————-—-———— 10. [6.5 points] [Exam #32] _______________________________———————————— A rain drop falls about 1000m before hitting the ground. Why does the rain not cause damage, even though under constant acceleration a drop would have a speed of 140 m/s (~313 mph) just before it hits the ground? . A. Gravi does not act on liquids. . None of the other choices is trueg 7r ‘ " C. The earth's magnetic field exerts a force that prevents rain drops from acquiring that much speed. D. Rain drops are very small- 9 W3 +g ream ' @ Rod nay/0P3 Cure S’I‘Vovrjl Ot—FFechecp [6.5 points] ‘ bté/ our Ovrofl as Md all. Wafer“ yyb/flw arm 02.» not baa/totem o owstamt accede/rectum CO; raj/rotmp has onst carom/«Md Gnu/5 VOW MINUS g A simia/rhj SWL“ Pfaca oi— (Mama-1A1 owl. ,Hmoggl szpois VOW/Joe bee Howwrxl ~H~°~ mil/lake? is pls'eroy/Jrablz, go flu: Stopping 01?sz .‘g W flan/x0124) 50 “HM; amlwdfm’Ma/t firm/x3 m 4w» ragga/<14, is m/mwwr 3mm. (mffmrgorca 0'” ‘HNL obj Lot Join? 4M stopping (firmd. wn'naiooo, Mjkmol, {+97 is FUMNIOW 3mm. _____________________________._—————————————-- ' 11. [6.5 points] [Exam #32] ___________________________’——————————-—- A space station is shaped like a ring and rotates to simulate gravity. If the radius of the Space station is R: 120 113, How fast must it rotate (in terms of time taken for one complete turn) so that it simulates Earth's gravity? [Hints The apparent weight of the astronauts must be the same as their weight on Earth] ‘ A. 31.3 seconds C. 55.6 seconds; V_ j - p D. 27.8 seconds V ‘ t E; 41.7 seconds - .7 I r ‘ r”. , m s+m+€m objtci- in m S? K .4' v y. T N Dbjior 9- l God 2:: - N ~ 277;— «mi/Wm "F = [El—EB (b'rvu. it films new we V OOMPiL—f‘g, +urn3 wz wamt flue OvFFQAAal/Li‘ magi/xi) N‘ 016 “PM asirendw‘l's +0 {on flaw +0 1M? . ,M3- PM,“ K W=V JETR T7W 12. [6.5 points] [Exam #32] M A man lifts a 2.0 kg stone vertically with his hand at a constant upward acceleration of 1.5 m/sz. What is the magnitude of the total force of the stone on the man's hand? 1"“ . 23 N downward . N downward C. 32 N downward D. 17Ndownward ' 0,24“ka on m E. 11 N downward fifié’mm KPH” % mi“ be. 3rd Jiowo PM‘iWkMDL 0v 0? "Hug. Force. 01“ flaw-a“ [6.5 points] Shim _,——>'f W __________________________________’———————————-—’ 13. [6.5 points] [Exam #32] __________________________________——————————————" Tamar wants to cut down a large, dead poplar tree with her chain saw, but she does not want it to fall onto the nearby gazebo. Yoojin comes to help with a long rope. Yoojin, a physicist, suggests they tie the rope taut from the poplar to the oak tree and then pull sideways on the rope (the figure below). If the rope is 40.0 m long and Yoojin pulls sideways at the midpoint of the rope with a force of 360.0 N, causing a 2.00-m sideways displacement of the rope at its midpoint, what force will the rope exert on the poplar tree? [Hints Until the poplar is cut through enough to start falling, the rope is in equilibrium] A. 1660N ‘ ' B. 139ON* (c.1810NS _ _ . 1-2~70N; E. 1530 Nl' [6.5 points] _________________________.__——————-—-—-——— 14. [3.5 points] [Exam #32] E Consider two vehicles, a compact car and a large truck, that are both traveling around the turn in the road in the figure below and assume the coefficient of friction between the tires and the road is the same for both. The car can drive through the turn at the largest speed without slipping. Top View 1 A. False B. True [3.5poz'nts] ______________________________._—————-——————-' 15. [6.5 points] [Exam #32] wa \l ws A boat that can travel at 4.0 km/h in still water crosses a river with a current of 1.8 km/h. At What angle must the boat be pointed upstream to travel straight across the river? In other words, in what direction is the velocity of the boat relative to the water? A. 33°;upstream B. 37°;u stream C. 279;1_1pstream . .. a “D; 39' ;ups_trearn i J‘ H ' QE. 45?;upstream" " [6.5poz'nts] ' 16. [6.5 points] [Exam #32] ' Ask v . ' A boy has stacked two blocks on the floor so that a 5.0—k block is on top of a 2.0-kg block. (a) If the coefficient of static friction between the 0 blocks is [0.40 and the coefiicient of static friction between the bottom block and the floor isZO.22;iwith what force should the boy push on the upper block to make both blocks in the system to slide along the floor? (b) If he pushes too hard, the top block starts to slide off the lower bloc . What is the limit of the force with which he can push without that happening? B. (a) 69N; (b) 49N c. (a) 15 N; (b) 49N D. (a) 69 N; (b) 25N E. (a) 35 N; (b) 20N [6.5 points] /r ' 'Mst d «Hm, blacks—{a S’hMi' Shall I ' é J j - ' Should be mam. - mam +W- floor at w biog}: éFy :- C’) '2 FFuSlfl— Esme»): ,C.F'Fwsh —- M§f‘(m5+mg)3 st“ b MW be mod hat—Flashes "+00 hourci, beinLPH ‘Hw. ioloolcs will owt ' lawshlmf Mu, Mama. [Wash imm I M55 m5? ridicm ___________________________'.——————————-—-—' 17. [6.5 points] [Exam #32] __________________________________———-——————--—-—- A brick of mass 2.00 kg is weighed under water by hanging it from a spring scale (similar to that shown in the figure below). (a) If the spring scale reads 14.0 N, what is the upward force of water on the brick? (b) What is the reading of the pan scale on which the beaker sits? The weight of the water and the beaker together is 12.0 N. ____’————‘- [6.5p0ints] E. (3)5.0 N up; (b)15.2 w [H kmle. 0K +hiral W W ‘—Hm.:t push”: dawn on wqur‘ ________________________________.___—————-————- 18. [6.5 points] [Exam #32] , ___________________________________————-———— Spring scale A is attached to the floor and a rope runs vertically upward, loops over the pulley, and runs down on the other side to a 120-N weight (the figure below (part b)). Scale B is attached to the ceiling and the pulley is hung below it. What are the readings of the two spring scales, A and B? Neglect the weights of the pulley and scales. A. Scale Areads 120 N; B reads 240 N Scales A and B read 240 N C.‘ scale Are'ads 240 N and Scale B reads 120 N D. Scales A and B read 120 N E. Scales A and B read 0 N [6.5 points] I ___________________________—_——————————-—-- 19. [6.5 points] [Exam #32] __________________________——————————-—-—- A person is standing on a bathroom scale. Identify the third-law partner of each of the forces exerted on the scale. In other words, for every interaction involving the scale, identify the force that the scale exerts on another object. A. The scale exerts an downward gravitational force on the Earth, while the Earth exerts a upward gravitational force on the scale. The scale exerts an downward force on the person, while the person exerts a upward force on the scale. The scale exerts a downward force on the floor, while the floor exerts an upward force on the scale. B. The scale exerts an upward gravitational force on the Earth, while the Earth exerts a downward gravitational force on the scale. The scale exerts an upward force on the person, while the person exerts a upward force on the scale. The scale exerts a downward force on the floor, while the floor exerts an downward force on the scale. C. The scale exerts an downward gravitational force on the Earth, while the Earth exerts a upward gravitational force on the scale. The scale exerts an upward force on the person, while the person exerts a downward force on the scale. The scale exerts a upward force on the floor, while the floor exerts an downward force on the scale. D. The scale exerts an upward gravitational force on the Earth, while the Earth exerts a downward gravitational force on the scale. The scale exerts an upward force on the person, while the person exerts a downward force on the scale. The scale exerts a downward force on the floor, while the floor exerts an upward force on the scale. [6.5 points] ______________________—_______—_______-_——___— 20. [6.5 points] [Exam #32] __________________________________—____——————-— An unmarked police car starts from rest just as a speeding car passes at a speed of v0 . If the police car accelerates at a constant value of a, what is the speed of the police car when he catches up to the Speeder, who does not realize she is being pursued and does not vary her speed? A. 3V0 B. 0.5V0 C. V0 D. 4V0 [6.5pbints] , CHIP ID: 32LOR U 73 43 (This question has been adapted from codes originally written by and for WebAssign.) fior ,sz. 190(le W +0 Carl—0V1 ‘l’lmp Sfmu'nj (10%) «Hwy lam/CL +0 COVLV «ML SW dl.s+w% m W SW ’H’lwbl "MM is\ {Wolf MUG-g: VU/JOGII‘HQaS “AIMS—l Sad/PU?» ana/ + Spmflu'rtj W is not Vowjmf}, Spud, .16 ocvmo‘jz spael WHAS'l‘ 10L v0. For M object with COHSJLM?‘ MWIUMW Jr .n . Vt, “It .a ,‘tstow Q War SW“ * T a WWW m so \Io=—\L§ ~> V4319“) ...
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This note was uploaded on 12/07/2011 for the course PHYS 220 taught by Professor Chang during the Fall '09 term at Purdue.

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Exam1Solutions - 1[3.5...

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