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Unformatted text preview: This print-out should have 14 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Suppose that you wish to find out how much gasoline is in an underground storage tank. You pour in one gallon of gasoline that con- tains some long half-life radioactive mate- rial that causes a Geiger constant to register 46800 counts per minute above background radiation. The next day you remove a gal- lon from the underground tank and measure its radioactivity to be 100 counts per minute above background. How much gasoline is in the tank? Correct answer: 468 gallons. Explanation: There are 468 gallons of gasoline in the storage tank. We know this because af- ter mixing, the gallon you withdraw has 100 / 46800 = 1 / 468 of the original radioac- tive particles in it. So the withdrawn gallon is 1 / 468 of the total volume of gasoline in the tank. The same method can be used to measure the volume of blood in creatures-including hu- mans. Information about blood flow as well as volume is obtained by injecting radioisotopes such as chromium-51 into the bloodstream. See Paul Hewitts books for more examples of Figuring Physics. 002 (part 1 of 2) 10.0 points The mean radius of a planet is 6 . 79 10 6 m, and that of its moon is 1 . 85 10 8 cm. From this data calculate the ratio of the planets surface area to that of its moon. Correct answer: 13 . 4709. Explanation: The surface area of a sphere is 4 R 2 , so the area ratio is A planet A moon = 4 R 2 planet 4 R 2 moon = R 2 planet R 2 moon = 13 . 4709 ....
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This note was uploaded on 03/26/2010 for the course PHY 303K taught by Professor Turner during the Fall '08 term at University of Texas at Austin.
- Fall '08