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exam 3 solutions - EXAM 3 Physics 122 Thursday, April 19th...

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Unformatted text preview: EXAM 3 Physics 122 Thursday, April 19th IMPORTANT: No scratch sheets or additional paper is allowed on this exam. This test has 4 multiple-choice questions and 4 problems to be worked out. To assist in grading - please place the answer to each question parting the box provided. Show your calculations, methods, and approach clearly where possible. Showing your work will increase your chances of receiving partial credit. You have one hour to work the exam. Use g = 10.0 m/s2 for all problems. Assume all problems have three significant figures. Talking or looking at a neighbor’s exam will be considered academic dishonesty. Use the s ace rovided on this exam only. NAME: EEC: A WE DO NOT OPEN THIS TEST UNTIL TOLD TO DO SO! NO CALCULATORS! For Instructors Use only: Problem Score Grader MC 5 6 7 8 1. A box is moving on a tilted conveyor belt. Express its change in potential energy, as it goes from point A to B, a distance Ah higher. a. mg(Ah) UL k; MCI/H: b. -mg(Ah) _._. — “:M‘ 3‘ ' C. mg (TA—1‘13) ALL L (1. mg (rB—rA) .1 m [3k 2. A traveler pulls a suitcase strap at an angle 360 above the horizontal. If 400 J of work are done by the strap while moving the suitcase a horizontal distance of 10 m, what is the tension in the strap? .— a. 4000 (cos 36°) v”; UK): ‘4 (30?) b. 40/(cos36°) F i h — \COSCQ c. 400/(sin36°) _ W “ k0 ' j ‘ 90ch d. 40(sin360) 3w F ___ 7., 3:“; : my? I I ‘ lax!“ xx.) .3 MM“ 3. What is the magnitude of free fall acceleration of a ball of mass m, and radius rb on a planet of mass Mp and radius Rp? a GM Pmb / j a ' RPZ 3 l b GM P WV C: ~:— [We {Vi/D R 2 £3 .flwwmim” P R GM Pmb P c. 2 r}; d. 9.8 m/s2 4. An earth satellite needs to have its orbit changed so the new orbit will be twice as far from the center of the orbit as the original orbit. The new orbit period will be twice as long as the original period. a. True , ,Z ‘ 3 b. False T “7H2 h 5. A uniform meter stick (mass = 2.0 kg) is free to rotate about a frictionless pivot at one end (Icm = (1/ 12) mLZ). The rod is released from rest when it makes an angle of 30° with respect to the vertical. sin 30° = 0.50, cos 30° = 0.87 a. What is the moment of inertia of the rod about its new axis of revolution? Is the rotation clockwise or counterclockwise? Be sure to draw a figure showing the rods orientation and the forces acting. 2 Ipmnllel :— Icm % rind -: ' Z ‘_ 3 Z YVlL. (NF b. What is the net torque acting on the rod? Is the rotation clockwise or counterclockwise? Be sure to draw a figure showing the rods orientation and the forces acting. lefill: M“ 7.173.116 m} Z r Kym/E : .‘LY‘ 3H130(20kfil(10( J g i . , z r. VF:- Ec/QO I m c. What is the magnitude of the angular acceleration, in rad/s2, at the instant it is released? ”f-;J:Q< _ ix: 1 Z 45100”) w Z fl ids : 71.5 rad/S Z 1: 3‘ (masfllml a (A "3 7‘3 Pad/SZ ) —u 6. A 10.0 m board sits on two saw horses as "1 shown. The board has a mass of 360 kg. Use the conditions of static equilibrium to find the magnitudes of the normal forces I11 and n2. 1.0m (Min? 3 Q} n] 3: It G 4 . ,»_. _ O m1 LL: ,,_ 4» n "' . . « - - ——/ " n “TH/"l ( 3G7O ( H) ,0 IW/S a\ 9m C 18 fl 1 i ’C’ « 2000 M V\\ fl' LL) “fl 2 : “9001\1 V 7_ A solid disk (1w = 1/2 Inrz) is released from rest and rolls without slipping down an inclined plane. a. What is the rotational kinetic energy of the disk in terms of algebraic symbols? K ‘ Ler ~\/;mo ‘2 / Z L - ’Z. \/ ,/ 7 :Wmmw r Q1, ,2 ’ q HOV .L, ,1 b. Using conservation of energy determine the speed of the disk after it has rolled 5.00 m, measured along the plane (4.00 m horizontally)? Et 4 Gt; [ : KP F? J_ 3:. i“ mch firm/7 ‘“ 2- ‘ W2 i mCWL' > imv’v‘ "' ‘i “N a 1 3 Z ’ M\/ i \l 1, Y5 WWW) gaméi icor Wars? (7173 A+ B 8. A spring compressed 0.100 m pushes a ball attached to a string. The: spring constant is k =2000 kg/s2 and the ball has a mass of 1.00 kg. a. How high does the ball swing, hmax? :11 L: L. ; 0 «I o . \ w (,k 1‘ i M —' («(7/ + Before Afier L )4 (‘53 c“ 3 mahmax' z; W2 hmay -: ‘52 j ‘ m “2 2m; ZUCmL-CSMW /s' 3 b. If the bail swings down from its highest point hmax to half the value of this height (1/2 hm”), what is the magnitude of the ball’s velocity there? (a Child—gdfi'fi-VKP ’ Z mlgifimax : “é” 0‘8th "' MV fihmw (L iz.\ A: Jév z a Z iiflkmcw : V l / VI“ -: \( mom/3'2. ( LOO M I '{n X EXAM 3 Physics 122 Thursday, April 19th IMPORTANT: N0 scratch sheets or additional paper is allowed on this exam. this exam only. This test has 4 multiple-choice questions and 4 problems to be worked out. To assist in grading -- please place the answer to each question parting the box provided. Show your calculations, methods, and approach clearly where possible. Showing your work will increase your chances of receiving partial credit. You have one hour to work the exam. Use g = 10.0 m/s2 for all problems. Assume all problems have three significant figures. Talking or looking at a neighbor’s exam will be considered academic dishonesty. Use the s ace rovided on B DO NOT OPEN THIS TEST UNTIL TOLD TO DO SO! NO CALCULATORS! For Instructors Use only: Problem Score Grader MC OO\]O\UI B l. A box is moving on a tilted conveyor belt. Express its change in potential energy, as it goes from point A to B, a distance Ah higher. a. mg (rB ~ rA) b. -mg(Ah) -:' y,u\:ml\£‘m*i’l' c. mg(Ah) A“ tip L 8 8 L d. mg(rA—rB) T. MC) Ola 2. A traveler pulls a suitcase strap at an angle 36° above the horizontal. If 400 J of work are done by the strap while moving the suitcase a horizontal distance of 10 Hi, what is the tension in the strap? __ . a. 40 (sin 36°) I LL) 5* F—& C (33 ® ‘ b. 4000 (cos 36°) " "7 __ T. U; _ L/GQT c. 400/(sin 36°) 1’ 3 = 4% - , , d. 40 I (cos 3(0 0 ’0 m l————~/ 20m 3. What is the magnitude of free fall acceleration of a ball of mass 111., and radius rb on a planet of mass Mp and radius Rp? a GMPmb H ,— ‘ R; be} ”' V6; b. GMT” 0/ : G: WW: rb b 2 C GMP RF . RPZ d. 9.8 m/s2 4. An earth satellite needs to have its orbit changed so the new orbit will be twice as far from the center of the orbit as the original orbit. The new orbit period will be four times as long as the original period. a. True , 3 b. False T249 E 5. A uniform meter stick (mass = 2.0 kg) is free to rotate about a fiictionless pivot at one end (Icm = (1/12) mLZ). The rod is released from rest when it makes an angle of 60° with respect to the horizontal. sin 600 = 0.87, cos 60° = 0.5 a. What is the moment of inertia of the rod about its new axis of revolution? ls—the the rods . orientation'and‘the“forcesaeting.— H LmL’Z'f in (“L/Z Z gm b. What is the net torque acting on the rod? Is the rotation clockwise or counterclockwise? Be sure to draw a figure showing the rods orientation and the forces acting. 2 if"), F: f", 9:- ‘z r g In / L LA.) 2/ — :— a w 1., / CU“) Z 9' c. What is the magnitude of the angular acceleration, in rad/s2, at the instant it is released? ,l’Xt‘ :_ g: k z x. ‘- fv,‘ r”? r61 .1 -Smm a p a 75 5 at A: r M g is e 75¢:szme 6. A 10.0 m board sits on two saw horses as shown. The board has a mass of 360 kg. Use the conditions of static equilibrium to find the magnitudes of the normal forces In and n2. fF:O nf +111 -‘UJ :- O 27%: C: ~C e 7. A solid disk (ICM = 1/2 mrz) is released from rest and rolls without slipping down an inclined plane. a. What is the rotational kinetic energy of the disk in terms of algebraic symbols? . ._ ' _____ ' KK"J5J,u:>Z Z V iv, J; J. W, T; “7 t: 2%‘mv’w : mu b. Using conservation of energy determine the speed of the disk after it has rolled 5.00 m, measured along the plane (3.00 m horizontally)? A C¢=GP M/ . ' .. ’ {grilfl gm (AL ’ Rf; 2 if :2 WWW ‘ fiLmV ’* Z“ “’2 \ W Z i m U l O> ’“l m lm" “W l" “‘ _._. z a 2 Qj‘lh‘ : ‘23" ‘04" k //_:__~____\ :Y Li (poem/51) Hm) 5 1,- %0 m/fi to: o _. is" "7-8 ...
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This note was uploaded on 04/21/2008 for the course PHYS 122 taught by Professor Pope during the Spring '08 term at Clemson.

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exam 3 solutions - EXAM 3 Physics 122 Thursday, April 19th...

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