Summary hw 4

Summary hw 4 - 0[U 7L Total grade PH 1110 Summary Homework 4 C Term 2008 Name Section Number This assignment is worth 2.5 of your final grade and

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Unformatted text preview: 0 [U 7L! . Total grade: PH 1110 Summary Homework 4, C Term 2008 Name Section Number ' This assignment is worth 2.5% of your final grade and is our recommended means for you to assess your readiness for Exam 4. It is due in conference on Thursday, February 21, and will be returned to you in conference on Tuesday, February 26, the day before Exam 4. Please Show your work and report your answers to no more than three significant figures. Place your answers in the boxes, where provided. This summary homework covers the first three-fiiurths of the material in Study Guide 4. The last page of this study guide is a non-credit supplementary problem covering the. lost fourth of the material, which you should solve and bring to conference on Tuesday, February 26, when it Will be discussed. 1a. [5 pts] In Lab 8, you verified the conditions for static equilibrium. State these conditions here, in either sentences or equations. «.3 ino 25150 01 EFT-0 7‘ ‘) 2+:0 1b. [20 pts] Ifthree forces are acting on the stick that you used in Lab 8, and two forces and their position vectors are lmown and given below, find the third force and the torque that the third force exerts upon the stiCk, which is in equilibrium. The coordinate system is shown on the sketch for part c).. The first two forces and their position vectors are: [rm-q F1 = ( + 2.00 i + 2.00 j) N r1 = 7.00 i cm F2=(—0.700i—1.40j)N r2=10.0icm A . 7 Mr; t—li‘lOKIOrIO—z = —I4>‘/0'1U-M . Mr, wrung: :3 rszo Is=| 0 1 1c. [15 pts] Sketch the three force vectors on this diagram in their correct positions. The end-to-end length of the stick is 11.4 cm. in 1 Points earned on this page: ':I . Summary Homework 4, continued. Name 4/“ i < 3 Section Number 2a. [10 pts] In Lab 9, in a now very familiar arrangement, a string connecting a cart and a hanger went over a pulley, as in the sketch below on the leflz. The pulley has tensions T1 and T2 acting upon it, as shown below in the center. Write an expression for the total torque vector on the pulley in terms of the shown variables. Assume no slip between the string and the pulley throughout this problem. A TI Experimental set-up Close'up 0f Pulley Trot: 77"” *- 2b. [10 pts} Given that the pulley has a moment of inertia of I = 1.00 x 104 kg n12, T1 1 4.40 N, T2 = 4.39 N, and r = 2.50 cm, what is the magnitude of the angular aCceleration of the pulley? Z"?—‘ZP< W tr. ma 2 Id x 2 ('2: a DA 20. [10 pts] The pulley starts rotafig at t = 0 3. At t = 10-0 5, through how many radians has it revolved? e :2 JL oi {,7' 1. I z. L 2.5“. to 2e. [10 pts} What is the work done on the pulley during this time? ‘ .N, ..__. J. 2 _ .L f” w " 2. I w; L I we. a»; 1.00 No” (29‘)2 -- C) pts] What is the angular speed at t = 10.0 s? m] 9 it eagle) = 2.53/0 2f. [10 pts] If all of the kinetic energy of the pulley were to be converted into raising a 3.00—g mass up from the floor, to what height h would the mass be lifted? , ___ ' _h = f.- 0 6 m 3 X! 0‘3 X ‘71 3’ ' w = M f) h 2 ' I Points earned on this page: :. \t ," “1. Supplementary Problem on Angular Momentum xii; _ , “La-u.) Solve this non—credit problem and bring it to conference on Tuesday, October 9. It is intended to give you practice on the material in the last part omedy Guide 4. A large turntable with moment of inertia l = 1000 kg m2 spins with angular speed to 2 3.00 rad/s. Person A, mass mA = 60.0 kg stands at a distance halfiNay to the outer edge of the turntable, whereas Person B, mass m3 = 80.0 kg stands right at the outer edge of the turntable, as shown below. The people can be regarded as point masses for this problem, and the radius of the turntable r = 5.00 m. What is the angular speed of the turntable after person A walks to the center of the tame? Li 5 L3; . ' "‘ 2* - e(I+an-+mn?’)w (I 4" mAfl-mi + Maneé'u"; a; k M at” e [£000 4- (go (25)“ 4. 30(szflw- $0000 + o a WES) J50? w; 2 3, as a/s Person B jumps oft‘the turntable in a direction parallel to his instantaneous velocity, with speed 5.00 m/s relative to the ground. What is angular speed of the turntable now? I‘d-“Lee E“- wwmwa) as; S I Na + we Cteoo +90C7DL3 3.38 :1 [000 a)“: + YOxS‘xf’)" to g z 9.12 12/5 4: ?erson B now returns to the side of the turntable and stands on the ground. He places his hands on the side of the tumtable, causing a friction force of 100 N. How many revolutions does the turntable make before coming to rest? . i 2' 7'9 = File 5 Eerwerr a. a : J; ((000)08’. I2.) 100K5- g) e‘éé‘O ’5 ‘2 l 0, 5.] AR tie/wiring ' ' 3 I Points earned on this page: ...
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This homework help was uploaded on 04/09/2008 for the course PH 1120 taught by Professor Keil during the Spring '08 term at WPI.

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Summary hw 4 - 0[U 7L Total grade PH 1110 Summary Homework 4 C Term 2008 Name Section Number This assignment is worth 2.5 of your final grade and

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