Ch18-h1-solutions

Ch18-h1-solutions - liu(ql744 Ch18-h1 chiu(56565 This...

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This print-out should have 37 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points The vectors ± a and ± b both lie in the xz plane. The vector ± c is equal to ± a × ± b. Which oF these statements about ± c must be true? 1. None apply. 2. The z and x components oF ± c are zero. correct 3. The y and z components oF ± c are zero. 4. The x and y components oF ± c are zero. Explanation: ± c is to the plane oF ± a and ± b. Thus, ± c is in the ± y direction. ThereFore, the vector is only nonzero in the y direction. 002 (part 1 of 6) 5.0 points Av ec to r ± C oF magnitude 7 lies along the x axis, and a vector ± D oF magnitude 8 lies in the xy plane, 30 From the x axis (±igure 18.71). ±ind the magnitude and direction oF ± A x ,A y z ² iF ± A = ± C × ± D . x y z 30 C =7 D =8 What is the magnitude and direction oF A x ? Correct answer: 0. Explanation: ± C = ± 7 , 0 , 0 ² and ± D = ± 8cos(30) , 8sin(30) , 0 ² so ± C × ± D = ± ( C y D z - C z D y ) , ( C z D x - C x D z ) , ( C x D y - C y D x ) ² = ± 0 , 0 , 28 ² ThereFore, this vector is only in the + z direction and has a magnitude oF 28 . 003 (part 2 of 6) 5.0 points What is the magnitude and direction oF A y iF ± A = ± C × ± D ? Correct answer: 0. Explanation: See Explanation 1. 004 (part 3 of 6) 5.0 points What is the magnitude and direction oF A z iF ± A = ± C × ± D ? Correct answer: 28. Explanation: See Explanation 1. 005 (part 4 of 6) 5.0 points What is the magnitude and direction oF A x iF ± A = ± D × ± C ? Correct answer: 0. Explanation: ± D × ± C = - ± C × ± D = ± 0 , 0 , - 28 ² ThereFore, this vector is only in the - z direction and has a magnitude oF 28 . 006 (part 5 of 6) 5.0 points What is the magnitude and direction oF A y iF ± A = ± D × ± C ? Correct answer: 0. Explanation: See Explanation 4.
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007 (part 6 of 6) 5.0 points What is the magnitude and direction of A z if ± A = ± D × ± C ? Correct answer: - 28. Explanation: See Explanation 4. 008 (part 1 of 3) 10.0 points ± A = ± 4 , 3 , - 10 ²×±- 9 , 10 , 0 ² What is A x ? Correct answer: 100. Explanation: ± A = ± 4 , 3 , - 10 9 , 10 , 0 ² = ± [(3)(0) - ( - 10)(10)] , [(3)( - 9) - (4)(0)] , [(4)(10) - (3)( - 9)] ² = ± 100 , 90 , 67 ² 009 (part 2 of 3) 10.0 points What is A y ? Correct answer: 90. Explanation: See Explanation 1. 010 (part 3 of 3) 10.0 points What is A z ? Correct answer: 67. Explanation: See Explanation 1. 011 (part 1 of 3) 10.0 points ± A = ± v × ˆ r .F ind ± A if ± v = ± 450 , - 450 , 322 ² m/s and ˆ r = ± 0 . 577 , 0 . 577 , - 0 . 577 ² . What is A x ? Correct answer: 73 . 856 m / s. Explanation: ± A = ± v x ,v y z ²×± r x ,r y z ² = ± ( v y · r z - v z · r y ) , ( v z · r x - v x · r z ) , ( v x · r y - v y · r x ) ² = ± ( - 450)( - 0 . 577) - (322)(0 . 577) , ( - 450)(0 . 577) - (450)( - 0 . 577) , (450)(0 . 577) - ( - 450)(0 . 577) ² = ± 73 . 856 m / s , 445 . 444 m / s , 519 . 3m / s ² 012 (part 2 of 3) 10.0 points What is A y ? Correct answer: 445 . 444 m / s. Explanation: See Explanation 1. 013 (part 3 of 3) 10.0 points What is A z ? Correct answer: 519 . / s. Explanation: See Explanation 1. 014 (part 1 of 3) 10.0 points Consider the diagram below. The locations marked A, B, C, and D are all equidistant from the positive charge at the origin. Con- sider the unit vectors pointing toward those locations and the cross products ± v × ˆ r .
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This note was uploaded on 10/25/2011 for the course PHY 303L taught by Professor Turner during the Spring '08 term at University of Texas.

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Ch18-h1-solutions - liu(ql744 Ch18-h1 chiu(56565 This...

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