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Unformatted text preview: Patel (pnp223) homework 14 Turner (92160) 1 This printout should have 8 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A billionaire offers to give you $3 . 2 billion if you will count out the amount in $1 bills or a lump sum of $8000. Assume that you can count at an average rate of one bill per second, and be sure to allow for the fact that you need about 10 hours a day for sleeping and eating. Which offer should you accept? In order to answer this, how long will it take you to count out the $3 . 2 billion? Correct answer: 174 years. Explanation: Basic Concepts: 1 h = 3600 s 1 yr = 365 days Given: n = 3 . 2 10 9 bills 1 day = 14 h Solution: n = ( 3 . 2 10 9 bills ) 1 s 1 bill 1 h 3600 s 1 day 14 h 1 yr 365 days = 174 years Take the $8000. It would take 174 years to count 3 . 2 billion $1 bills. 002 10.0 points The acceleration due to gravity on planet X is one fifth that on the surface of the earth. If it takes 3 s for an object to fall a certain distance from rest on earth, how long would it take to fall the same distance on planet X? Correct answer: 6 . 7082 s. Explanation: Because the acceleration due to gravity is uniform near the surface of both planets, the distance an object falls in a time t is given by x fall = g planet t 2 2 where g planet is the force of gravity near the surface of the given planet. Since the distance x fall is the same for both planets, then x fall = g e t 2 e 2 = g x t 2 x 2 = 1 5 g e t 2 x 2 t 2 e = 1 5 t 2 x t x = 5 t e = 5(3 s) = 6 . 7082 s . 003 10.0 points A bee wants to fly to a flower located due North of the hive on a windy day. The wind blows from East to West at speed 6 . 48 m / s. The airspeed of the bee ( i.e. , its speed relative to the air) is 12 . 2 m / s. In which direction should the bee head in order to fly directly to the flower, due North relative to the ground? Correct answer: 32 . 083 East of North. Explanation: Bees velocity relative to the ground is a vector sum of its velocity relative to the air and the wind velocity (relative to the ground), vectorv bee ground = vectorv bee air + vectorv wind ....
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This note was uploaded on 07/11/2009 for the course PHY 92160 taught by Professor Turner during the Spring '09 term at University of Texas at Austin.
 Spring '09
 Turner
 Physics, Work

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