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Unformatted text preview: alexander (jra2623) homework 25 Turner (92510) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points Water is to be pumped to the top of the Empire State Building, which is 1200 ft high. What gauge pressure is needed in the wa ter line at the base of the building to raise the water to a height of 708 ft? Assume the den sity of water is 1000 kg / m 3 . The acceleration of gravity is 9 . 8 m / s 2 . Correct answer: 2 . 11472 10 6 Pa. Explanation: Let : h = 708 ft and = 1000 kg / m 3 . P g = P P atm = g h = ( 1000 kg / m 3 ) ( 9 . 8 m / s 2 ) (708 ft) parenleftbigg 1 m 3 . 281 ft parenrightbigg = 2 . 11472 10 6 Pa . keywords: 002 10.0 points The small piston of a hydraulic lift has a crosssectional area of 2 . 7 cm 2 and the large piston has an area of 43 cm 2 , as in the figure below. F 2 . 7 cm 2 area 43 cm 2 What force F must be applied to the small piston to maintain the load of 16 kN at a constant elevation? Correct answer: 1004 . 65 N. Explanation: Let : A 1 = 2 . 7 cm 2 , A 2 = 43 cm 2 , and W = 16 kN . According to Pascals law, the pressure ex erted on A 1 must be equal to the one exerted on A 2 . The pressure P 1 = F A 1 must be equal to the pressure P 2 = W A 2 due to the load. F A 1 = W A 2 , so F = A 1 A 2 W = (2 . 7 cm 2 ) (43 cm 2 ) (16000 N) = 1004 . 65 N . 003 10.0 points A simple Utube that is open at both ends is partially filled with a heavy liquid of density 1000 kg / m 3 . A liquid of density 582 kg / m 3 is then poured into one arm of the tube, forming a column 7 . 7 cm in height, as shown. h 7 . 7 cm light liquid 582 kg / m 3 heavy liquid 1000 kg / m 3 What is the difference in the heights of the two liquid surfaces? Correct answer: 3 . 2186 cm. alexander (jra2623) homework 25 Turner (92510) 2 Explanation: Let : = 7 . 7 cm , = 582 kg / m 3 , and h = 1000 kg / m 3 ....
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This note was uploaded on 10/20/2011 for the course PHY 302K taught by Professor Kaplunovsky during the Summer '08 term at University of Texas at Austin.
 Summer '08
 Kaplunovsky
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