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Unformatted text preview: MasteringPhysics: Assignment Print View http://session.masteringphysics.com/myct/assignmentPrint?assignm... 1 of 37 9/16/07 2:20 AM [ Print View ] physics 2211 MP01: Chapter 1 Due at 5:30pm on Wednesday, September 19, 2007 View Grading Details Converting Units: The Magic of 1 Learning Goal: To learn how to change units of physical quantities. Quantities with physical dimensions like length or time must be measured with respect to a unit , a standard for quantities with this dimension. For example, length can be measured in units of meters or feet, time in seconds or years, and velocity in meters per second. When solving problems in physics, it is necessary to use a consistent system of units such as the International System (abbreviated SI, for the French Systme International) or the more cumbersome English system. In the SI system, which is the preferred system in physics, mass is measured in kilograms, time in seconds, and length in meters. The necessity of using consistent units in a problem often forces you to convert some units from the given system into the system that you want to use for the problem. The key to unit conversion is to multiply (or divide) by a ratio of different units that equals one. This works because multiplying any quantity by one doesn't change it. To illustrate with length, if you know that , you can write . To convert inches to centimeters, you can multiply the number of inches times this fraction (since it equals one), cancel the inch unit in the denominator with the inch unit in the given length, and come up with a value for the length in centimeters. To convert centimeters to inches, you can divide by this ratio and cancel the centimeters. For all parts, notice that the units are already written after the answer box; don't try to write them in your answer also. Part A How many centimeters are there in a length 357.7 ? Express your answer in centimeters to three significant figures. ANSWER: 909 Sometimes you will need to change units twice to get the final unit that you want. Suppose that you know how to convert from centimeters to inches and from inches to feet. By doing both, in order, you can convert from centimeters to feet. [ Print ] MasteringPhysics: Assignment Print View http://session.masteringphysics.com/myct/assignmentPrint?assignm... 2 of 37 9/16/07 2:20 AM Part B Suppose that a particular artillery piece has a range = 1.250 10 4 . Find its range in miles. Use the facts that and . Part B.1 Convert yards to feet Part not displayed Express your answer in miles to three significant figures. ANSWER: 1.250 10 4 = 7.10 Often speed is given in miles per hour ( ), but in physics you will almost always work in SI units. Therefore, you must convert to meters per second ( )....
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