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Unformatted text preview: nav277 Homework 4 Odell (58340) 1 This printout should have 20 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points Find the volume, V , of the solid obtained by rotating the region bounded by y = 3 x , x = 2 , x = 4 , y = 0 about the xaxis. 1. V = 9 8 2. V = 9 8 3. V = 9 16 4. V = 9 16 5. V = 9 4 correct 6. V = 9 4 Explanation: The volume of the solid of revolution ob tained by rotating the graph of y = f ( x ) on [ a, b ] about the xaxis is given by volume = integraldisplay b a f ( x ) 2 dx . When f ( x ) = 3 x , a = 2 , b = 4 , therefore, V = integraldisplay 4 2 9 x 2 dx . Consequently, V = bracketleftbigg 9 x bracketrightbigg 4 2 = 9 4 . 002 10.0 points Find the volume, V , of the solid obtained by rotating the bounded region in the first quadrant enclosed by the graphs of y = x 2 , x = y 4 about the xaxis. 1. V = 5 12 cu. units 2. V = 1 2 cu. units 3. V = 7 15 cu. units 4. V = 7 15 cu. units correct 5. V = 1 2 cu. units 6. V = 5 12 cu. units Explanation: Since the graphs of y = x 2 , x = y 4 intersect at (0 , 0) and at (1 , 1) the bounded region in the first quadrant enclosed by their graphs is the shaded area shown in 1 1 nav277 Homework 4 Odell (58340) 2 Thus the volume of the solid of revolution generated by rotating this region about the xaxis is given by V = integraldisplay 1 braceleftBig ( x 1 / 4 ) 2 ( x 2 ) 2 bracerightBig dx = integraldisplay 1 braceleftBig x 1 2 x 4 bracerightBig dx = bracketleftbigg 2 3 x 3 2 1 5 x 5 bracketrightbigg 1 . Consequently, V = parenleftBig 2 3 1 5 parenrightBig = 7 15 cu. units . 003 10.0 points Find the volume, V , of the solid formed by rotating the region bounded by the graphs of y = x + 3 , y = 3 , x = 0 , x = 1 about the line y = 1. 1. V = 3 cu. units 2. V = 8 3 cu. units 3. V = 10 3 cu. units 4. V = 17 6 cu. units 5. V = 19 6 cu. units correct Explanation: The region bounded by the given curves is shown as the shaded area in 3 1 1 y x (not drawn to scale) and the line about which it is rotated is shown as the dotted line. Thus the volume generated when rotating this shaded region about the dotted line y = 1 is given by V = integraldisplay 1 braceleftBig ( y 1) 2 (3 1) 2 bracerightBig dx = integraldisplay 1 braceleftBig ( x + 2) 2 4 bracerightBig dx = integraldisplay 1 braceleftBig x + 4 x bracerightBig dx . Consequently, V = bracketleftbigg 1 2 x 2 + 8 3 x 3 / 2 bracketrightbigg 1 = 19 6 . 004 10.0 points A cap of a sphere is generated by rotating the shaded region in y 1 3 about the yaxis. Determine the volume of this cap when the radius of the sphere is 3 inches and the height of the cap is 1 inch. nav277 Homework 4 Odell (58340) 3 1. volume = 4 3 cu. ins 2. volume = 5 3 cu. ins 3. volume = 7 3 cu. ins 4. volume = 8 3 cu. ins correct 5. volume = 2 cu. ins Explanation:...
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This note was uploaded on 04/15/2011 for the course MATH 408 L taught by Professor Zheng during the Spring '10 term at University of Texas at Austin.
 Spring '10
 ZHENG

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