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Unformatted text preview: Create assignment, 00223, Homework 4, Sep 15 at 9:06 pm 1 This printout should have 14 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. The due time is Central time. Perpendicular Vectors 02 05:01, trigonometry, numeric, > 1 min, nor mal. 001 Two vectors of magnitudes 10 N and 20 N act at right angles to each other. What is the magnitude of their resultant? Correct answer: 22 . 3607 N. Explanation: The resultant of two vectors acting at right angles to each other is the hypotenuse of a right triangle, so f = q f 2 1 + f 2 2 = q (10 N) 2 + (20 N) 2 = 22 . 3607 N Hanging Weight 04 05:07, trigonometry, numeric, > 1 min, wordingvariable. 002 Consider the 700 N weight held by two cables shown below. The lefthand cable had tension T 2 and makes an angle of 2 with the ceiling. The righthand cable had tension 570 N and makes an angle of 55 with the ceiling. The righthand cable makes an angle of 55 with the ceiling and has a tension of 570 N . 700 N T 2 5 7 N 5 5 2 a) What is the tension T 2 in the lefthand cable slanted at an angle of 2 with respect to the wall? Correct answer: 401 . 518 N. Explanation: Observe the freebody diagram below. F 2 F 1 1 2 W g Note: The sum of the x and ycomponents of F 1 , F 2 , and W g are equal to zero. Given : W g = 700 N , F 1 = 570 N , 1 = 55 , and 2 = 90  . Basic Concept: Vertically and Horizontally, we have F x net = F x 1 F x 2 = 0 = F 1 cos 1 F 2 cos 2 = 0 (1) F y net = F y 1 + F y 2W g = 0 = F 1 sin 1 + F 2 sin 2W g = 0 (2) Solution: Using Eqs. 1 and 2, we have F x 2 = F 1 cos 1 (1) = (570 N)cos55 = 326 . 939 N , and F y 2 = F 3 F 1 sin 1 (2) = 700 N (570 N)sin55 = 700 N 466 . 917 N = 233 . 083 N , so F 2 = q ( F x 2 ) 2 + ( F y 2 ) 2 = q (326 . 939 N) 2 + (233 . 083 N) 2 = 401 . 518 N . Create assignment, 00223, Homework 4, Sep 15 at 9:06 pm 2 003 b) What is the angle 2 which the lefthand cable makes with respect to the ceiling? Correct answer: 35 . 4861 . Explanation: Using Eq. 2, we have 2 = arctan F y 1 F x 1 = arctan 466 . 917 N 326 . 939 N = 35 . 4861 . Three Forces 05:07, trigonometry, numeric, > 1 min, nor mal. 004 An object in equilibrium has three forces ex erted on it. A(n) 33 N force acts at 80 , and a(n) 44 N force acts at 60 . What is the direction of the third force? (Consider all angles to be measured counter clockwise from the positive xaxis.) Correct answer: 248 . 557 ....
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This note was uploaded on 05/06/2011 for the course PHYS 103N taught by Professor Chiu during the Spring '11 term at University of Texas at Austin.
 Spring '11
 Chiu
 Physics, Work

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