lee3 - excites» Physics 124 — Analytical Physics FIRST...

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Unformatted text preview: excites» Physics 124 — Analytical Physics FIRST COMMON HOUR EXAM Monday, Feb. 21, 2011 Professor Ron Gilman => <2 SIGN HERE NOW: The exam will last from 9:40 — 11:00 pm. 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, MI.) enter your last name, then fill in the empty circle for a blank, then enter your first name, another blank, and finally your middle initial. Under STUDENT # enter your 9~digit RUID Number. Enter124 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 9 = 9.8 m/s2, G = 6.67'><10~11 Nm2/kg2, mam}, = 6><1024 kg, rem}, = 6.4x106 m, [hoop = mr2, Isoliddisc = (1/2)m7"27 Isolidball = (2/5)m7n27 and Istickaboutend = Two masses hang from massless ropes attached at different radii to a l-kg pulley. The left mass, m1 2 5kg, hangs from a radius of 0.2 m; the right mass, m2 = 10kg, hangs from a radius of 0.1 m. There is friction between the rope and the pulley. The pulley is supported at its; c.m. What is the net torque on the pulley from the forces acting on it? y 1: ~: M‘J‘. ml\ % Coms'xclar 4h: CAM» 9!} 36w; “mar Mina 36m. (M WWW {bite =D\ 2; 3% WW6 «9% it, Caveman} d) 19.6N MA. FL (’tz=WL%VZ\ preMSQ/fe e) 196N each O‘WJLS'. Ms, 2 E5 :0 \ WK "FL:W\1C8 L Your professor puts several objects on an inclined plane. All roll without slipping down the inclined plane. Which gets to the bottom first? a) hollow sphere, radius r ZWZXfl Cal/\éerva‘lrlbh j = K‘\' P 1’ CDl/‘Sl7 b) solid cylinder, radius 7" L O\ c) solid cylinder, radius 27" ( solid sphere, radius 7" 5 ,v— ...Hiua’ sped 94 Weym, w *5 e) hollow cylinder, radius 27“ L MAW—Lb A. z] z OFFM éo+bwl The flywheel of an engine rotates at 10 rad/s with an applied power of 10 W. What is the frictional torque in the the engine? a 0.1 N-m h c) 10 N~m d) 100 N-m e) Cannot be determined from information given. A Do 2 {O ~ We. ml? "7%Ml’eswer’wa cle W” W (halls, m m ’15 Q War \fgvich'ou Tam- A 9 - \O €5.55 4. A 2.0 kg solid disc 0.5 m in radius (neglect its thickness) slides along a frictionless horizontal floor without rotating at a steady 2 m / s. What is the angular momentum of the disc about a point P on the floor? a) It depends on where along the floor P is ' 2. b) 0.25 kgom/s c 0.75 k'm7s m3 e) 8 kg-m s I»; _ h m» a, “a, a v8; _. v —> Em. L = PH; L = Zfi‘Pz ‘2 Va *W‘fl” ‘ MV‘Z “W M32“ i V 5::269, i L T ’9 ‘l’lA-e CUSC radiws. 5. Two identical solid balls start from rest at height h. The one on the left slides without rolling down the left smooth frictionless part of the track shown. The one on the right rolls without slipping down the right rough part of the track shown, with v = our. The balls hit on the smooth frictionless flat bottom part of the track. What is the ratio of weft/might just before the balls hit? a) 1 b) 5/ ‘ mm; d) 3/2 9) It depends on exactly where the balls hit. smooth R 2 t’ '7... . 7. (Q ’“l c l 6. A wire has a 1-m long segment of steel (Young’s modulus =_ 2 ' 1011 Pa) and a 1—m long segment of brass (Young’s modulus = 1 - 1011 Pa), for a total length of 2 m. The width of the brass wire is two times that of the steel wire, so the area of the brass wire is four times that of the steel w1re. When a weight W is hung from the ceiling by this wire, the steel segment stretches by 1 mm. By how much does the brass segment stretch? a 0.25mm ( -, Ae‘ 5- p...) A, m _. .._. ~—- »— 0.5mm d; A‘ e Z-Aei Y7. A} e) 4mm F V A62. 5 7i ‘ 2 <9. L 7. A machine part has the shape of a s31id.uniform sphere of mass 0.2 kg and radius 0.03 m. It is spinning about firifilionless axle through its center, but at one point on its equator it is scraping against metal, resulting in a friction force of 0.01 N at that point. Find its angular- acceleration. Jan? vim a) 1.2 rad/s2 (Z =xo< W2 Fr \0 A/ c: an? b) 2. Brad/s2 c) 3.6 rad/s2 04 == 2 d 4.2 rad s x 2-5: ww?‘ email-($345 m e 6.6 rad/s2 (The gem“ 8. An object is placed at the left end of a 20 kg, 5~m long beam.\It/is supported at the right end and at a distance 4 m from the right end. How heavy can the object be without the beam tipping over? ’- _. a) 0kg . , v ,, -zal b) 13.31% OOMAA-LLOM. Y; c) 20 kg Tax-wee wi‘W @BOEk) .. , .i 0: e) 80 kg W5?” L3 4 9. A 200—kg Physics Professor, being utterly frustrated with the students?_ re— sults, turns into a spherical black hole. Find the professor’s Schwarzschild radius-11043 R .. zen ..._. - 5 C2 ($033?” c 1-10“17m ~2§ d) 3-10—12m "=- 37‘l0 m e) 1~10‘6 m 10. The Martian moon Deimos has a diameter of about 12.6 km and a mass of about 2X1015 kg. Treating it as spherical, how fast do you have to throw a ball so that it circules Deimos, 2 m above the surface, so that you can catch it? a) < 2 m/s b) in the range 2 —> 4 m/s c) in the range 4 —> 6 m/s \ d) in the range 6 —> 8 m/s ) e >8 m/s , ( Rd Mm “E; X osnLéng 4'6 5 11. Two solid spheres, each with a mass of M = 10139 and radiust = 0.1m, touch one another. What is the magnitude of their gravitational force of attraction? Z V“ Z ‘ D k 2 a UN v Fggflzzgflxlo figxwl: ) 3 4 NW I (2 m 4% 7 (mm c . m _ - d) 6.7w107N ‘ R” 7— mflS's to /(/ e) 9.8m107N 12. Titan, a moon of Saturn, has a 16 day orbital period and an orbital radius of 1,222,000 km. What is the mass of Saturn? a < 1><1026 kg m Titan c) in the range (0.1 —> 1) ><1028 kg d) in the range (0.1 —> 1) ><1029 kg e) >1><1029kg .. .233? :> (\3‘: art“:— T" 43' l 2 (2“\7.‘_'§ S Zék “L M.W\ -Wl'1-M. 2:. 5MB 3 _’. “’- '\ W~1~W=Grffx M5 6— GT7“ 3 Y“ r 13. A satellite with a mass of 10109 was launched into a circular orbit 1000 km above the Earth’s surface (the Earth’s radius is 6.4 ‘ 106 m, the'Earth’s mass is 6 - 1024199). What is the total (kinetic + potential) energy of the satellite? Take the potential energy to be zero when the Earth and satellite are infinitely far apart. a) 134083 E ==x4+x> = (CWme)< “3- hams b) 27-108.] 2 2t— 0 —2.7-108J 1 2" 2 d) 5.4.10.1 : 4,.7MD‘W’Q. 6"“) “of :— 2.72H083 e) —5.4-108J i=3 v quuto m 14. A tall cylinder is partially filled with water. The cross sectional area of the cylinder is 2 m2, and on top of the water is a lid, tightly sealed against the sides but floating on the water. What is the change in pressure at the bottom of the cylinder when several students (one shown) with total mass 200 kg stand on the lid? . , a) There is no change in pressure. b) 100 Pa 0) 200 Pa ‘ ) d 980 Pa - e 1960 Pa 15. A rectangular wooden block of weight W floats with exactly one-half of its volume below the waterline. Masses are stacked on top of the block until the top of the block is level with the waterline. This requires 20 g of mass. What is the mass of the wooden block? b) 10g Waszfiyi ( 9(W‘g’ecélfl2 Cm g \m »> Li’s amazes ‘3 QM 00214333 =90)ng m+002¥g z 2 W=D.02kfi w 16. In a pipe of radius 0.1 In, the water flow 18 Zhgfs past a certain p01nt. What is the speed of the water further along the pipe Where it expands to a radius of 0.12 m? WW“ 3 45" A i: ’U’ZrAz b) 1.7 m/s A l c) 2.0 m/s v _ *1 _~ {In DA (V W\ .1) 2.4.0. 057,- ‘v. A ~ 2 :5. «57.1 e MW 4 L h e) 2.9 m/s 17. A u—shaped tube has mercury in the bottom, With density 13.6 times the density of water. 10 cm of water are poured into the right side. How much higher is the top of the water on the right side than is the top of the mercury on the left side? a) 0.7 cm b 0.8 cm i 10 cm e) 136 cm 0017 Or “Hie FraSEM/TB Wat/«91‘ Q6, “the, SW19 W 0 ~— 5 ~ x _ r: Ms. M t; ~ M 1x. Inl— W = 9;.) st mam -- 0,14cm 1M k2 (3 m 18. Water in a tube flows at 2 m/s. What is the change in pressure at a point 1 m higher Where the water flows at 1 m/s? Assume the density of water is 1000 kg/m3. a) 43300 Pa \ b) C) d) ) e —6800 Pa 0 Pa — the pressure does not change 6800 Pa 8300 Pa P~+ pg“ Hiya)“: Cal/15+ A P : Pm = 42 e (val-VA Wt OHM “~— .%11000%3(443g .( ’3” $300 Pq m.— .— 7. 4—,!— [email protected]+am. =—~ we; 2r ’6’ ==' (Dam *0,7ZMIM c: 4‘. Barn 2 2 ...
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This note was uploaded on 03/02/2012 for the course PHYSICS 124 taught by Professor Madey during the Spring '08 term at Rutgers.

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lee3 - excites» Physics 124 — Analytical Physics FIRST...

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