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Unformatted text preview: Platt, David Oldquiz 4 Due: Dec 4 2005, 4:00 am Inst: Ken Shih 1 This printout should have 28 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points The reflecting surfaces of two intersecting flat mirrors are at an angle of 69 , as shown in the figure. A light ray strikes the horizontal mirror at an angle of 45 with respect to the mirrors surface. 69 45 Figure is not drawn to scale. Calculate the angle . Correct answer: 42 . Explanation: Basic Concept: incident = reflected Solution: 1 2 Figure is to scale. The sum of the angles in a triangle is 180 . In the triangle on the left we have angles , 180  1 2 , and 180  2 2 , so 180 = + 180  1 2 + 180  2 2 , or 1 + 2 = 2 . (1) In the triangle on the right we have angles 1 , 2 , and . 180 = 1 + 2 + , so 1 + 2 = 180  . (2) Combining Eq. 1 and 2, we have = 180  2 = 180  2(69 ) = 42 . As a matter of interest, in the upperhalf of the figure the angles (clockwise) in the triangles from left to right are 45 , 45 , and 90 ; 90 , 21 , and 69 ; 111 , 24 , and 45 ; 135 , 24 , and 21 ; and in the lowerhalf of the figure the angles (counterclockwise) in the triangles from left to right are 24 , 24 , and 132 ; 48 , 21 , and 111 ; 69 , 45 , and 66 ; 114 , 45 , and 21 . 002 (part 1 of 1) 10 points The reflecting surfaces of two intersecting flat mirrors are at an angle of 63 , as shown in the figure. A light ray strikes the horizon tal mirror, reflects off the horizontal mirror, impinges on the raised mirror, reflects off the raised mirror, and proceeds in the righthand direction. 63 Platt, David Oldquiz 4 Due: Dec 4 2005, 4:00 am Inst: Ken Shih 2 Figure is not drawn to scale. Calculate the angle . Correct answer: 54 . Explanation: Basic Concept: incident = reflected Solution: 1 2 Figure is to scale. The sum of the angles in a triangle is 180 . In the triangle on the left we have angles , 180  1 2 , and 180  2 2 , so 180 = + 180  1 2 + 180  2 2 , or 1 + 2 = 2 . (1) In the triangle on the right we have angles 1 , 2 , and . 180 = 1 + 2 + , so 1 + 2 = 180  . (2) Combining Eq. 1 and 2, we have = 180  2 = 180  2(63 ) = 54 . As a matter of interest, in the upperhalf of the figure the angles (clockwise) in the triangles from left to right are 46 , 46 , and 88 ; 92 , 27 , and 61 ; 119 , 17 , and 44 ; 136 , 17 , and 27 ; and in the lowerhalf of the figure the angles (counterclockwise) in the triangles from left to right are 17 , 17 , and 146...
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 Fall '08
 Turner
 Physics

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