18-1 - brown (twb493) – Ch18-h1 – chiu – (56565) 1...

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Unformatted text preview: brown (twb493) – Ch18-h1 – chiu – (56565) 1 This print-out should have 37 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points The vectors vectora and vector b both lie in the xz plane. The vector vectorc is equal to vectora × vector b. Which of these statements about vectorc must be true? 1. The z and x components of vectorc are zero. correct 2. None apply. 3. The x and y components of vectorc are zero. 4. The y and z components of vectorc are zero. Explanation: vectorc is ⊥ to the plane of vectora and vector b. Thus, vectorc is in the ± y direction. Therefore, the vector is only nonzero in the y direction. 002 (part 1 of 6) 5.0 points A vector vector C of magnitude 4 lies along the x axis, and a vector vector D of magnitude 6 lies in the xy plane, 32 ◦ from the x axis (Figure 18.71). Find the magnitude and direction of ( A x , A y , A z ) if vector A = vector C × vector D . x y z 32 ◦ C = 4 D = 6 What is the magnitude and direction of A x ? Correct answer: 0. Explanation: vector C = ( 4 , , ) and vector D = ( 6 cos(32) , 6 sin(32) , ) so vector C × vector 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 ) ) = ( , , 12 . 7181 ) Therefore, this vector is only in the + z direction and has a magnitude of 12 . 7181 . 003 (part 2 of 6) 5.0 points What is the magnitude and direction of A y if vector A = vector C × vector 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 vector A = vector C × vector D ? Correct answer: 12 . 7181. Explanation: See Explanation 1. 005 (part 4 of 6) 5.0 points What is the magnitude and direction of A x if vector A = vector D × vector C ? Correct answer: 0. Explanation: vector D × vector C = − vector C × vector D = ( , , − 12 . 7181 ) Therefore, this vector is only in the − z direction and has a magnitude of 12 . 7181 . 006 (part 5 of 6) 5.0 points What is the magnitude and direction of A y if vector A = vector D × vector C ? Correct answer: 0. Explanation: See Explanation 4. brown (twb493) – Ch18-h1 – chiu – (56565) 2 007 (part 6 of 6) 5.0 points What is the magnitude and direction of A z if vector A = vector D × vector C ? Correct answer: − 12 . 7181. Explanation: See Explanation 4. 008 (part 1 of 3) 10.0 points vector A = (− 1 , 2 , − 4 ) × (− 2 , − 10 , − 10 ) What is A x ? Correct answer: − 60. Explanation: vector A = (− 1 , 2 , − 4 ) × (− 2 , − 10 , − 10 ) = ( [(2)( − 10) − ( − 4)( − 10)] , [(2)( − 2) − ( − 1)( − 10)] , [( − 1)( − 10) − (2)( − 2)] ) = (− 60 , − 2 , 14 ) 009 (part 2 of 3) 10.0 points What is A y ?...
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This note was uploaded on 12/01/2011 for the course PHY 303L taught by Professor Turner during the Fall '08 term at University of Texas at Austin.

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18-1 - brown (twb493) – Ch18-h1 – chiu – (56565) 1...

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