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Unformatted text preview: Bautista, Aldo – Finalexam 1 – Due: Dec 15 2005, noon – Inst: Maxim Tsoi 1 This printout should have 40 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 A PingPong ball with mass 5 g is attached by a thread to the bottom of a beaker. When the beaker is filled with water so that the ball is totally submerged, the tension in the thread is 0 . 026 N. The density of water is 1000 kg / m 3 and the acceleration of gravity is 9 . 81 m / s 2 . 5 g Determine the diameter of the ball. Correct answer: 2 . 4538 cm. Explanation: Let : ρ w = 1000 kg / m 3 , g = 9 . 81 m / s 2 , T = 0 . 026 N , and m = 5 g = 0 . 005 kg . Consider the forces acting on the PingPong ball B mg T Applying Archimedes’ principle, we have B = w f = m f g = ρ w V ball g = 1 6 π ρ w g d 3 . Applying X F y = 0 to the ball, B mg T = 0 1 6 π ρ w g d 3 mg T = 0 . Then we have d = 3 s 6 ( T + mg ) π ρ w g = 3 s 6 [0 . 026 N + (0 . 005 kg) (9 . 81 m / s 2 )] π (1000 kg / m 3 ) (9 . 81 m / s 2 ) × 100 cm m = 2 . 4538 cm . 002 (part 1 of 1) 10 points The small piston of a hydraulic lift has a crosssectional area of 4 . 3 cm 2 and the large piston has an area of 21 cm 2 , as in the figure below. F 4 . 3 cm 2 area 21 cm 2 What force F must be applied to the small piston to raise a load of 32 kN? Correct answer: 6552 . 38 N. Explanation: Let : A 1 = 4 . 3 cm 2 , A 2 = 21 cm 2 , W = 32 kN , and F = F . According to Pascal’s 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 Bautista, Aldo – Finalexam 1 – Due: Dec 15 2005, noon – Inst: Maxim Tsoi 2 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 = (4 . 3 cm 2 ) (21 cm 2 ) (32000 N) = 6552 . 38 N . 003 (part 1 of 1) 10 points Before throwing a 0 . 834 kg discus, an ath lete rotates it along a circular path of radius 1 . 08 m. The maximum speed of the discus is 13 . 8 m / s. Determine the magnitude of its maximum radial acceleration. Correct answer: 176 . 333 m / s 2 . Explanation: The maximum radial acceleration is a r = v 2 r = (13 . 8 m / s) 2 1 . 08 m = 176 . 333 m / s 2 . 004 (part 1 of 1) 10 points A 1 meter long hose of 14 cm diameter is connected to a faucet. The end of this hose is connected to a second hose which is 4 meters long and 7 cm in diameter. At the open end of the second hose water flows out at a rate of 8 cm 3 /s. What is the ratio of the speed of the water flowing in the second hose to the speed of the water flowing in the first hose? 1. v 2 v 1 = 1 2. v 2 v 1 = 1 8 3. v 2 v 1 = 2 4. v 2 v 1 = 8 5....
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This note was uploaded on 10/13/2009 for the course PHY 303K taught by Professor Turner during the Fall '08 term at University of Texas.
 Fall '08
 Turner

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