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Unformatted text preview: Wong, Lemuel Homework 14 Due: May 6 2007, 11:00 pm Inst: Matt Mackie 1 This print-out should have 21 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. NOTE the due time is 11pm central, which is MIDNIGHT our time. 001 (part 1 of 2) 10 points Elliot is traveling by a building at 162835 km / s, moving along the width of the building. He measures the building to be 60 m wide and 110 m tall. What is the width of the building as mea- sured by a friend standing at rest next to the building? Correct answer: 71 . 4394 m. Explanation: The Lorentz factor is = 1 q 1- ( v c ) 2 = 1 p 1- (0 . 542783) 2 = 1 . 19066 To Elliot, the building appears to be con- tracted by a factor of 1 . 19066 in the di- rection he is moving. Thus the width is 1 . 19066 60 m = 71 . 4394 m . 002 (part 2 of 2) 10 points What height of the building would be mea- sured by the friend? Correct answer: 110 m. Explanation: To Elliot, the building appears to be con- tracted by a factor of 1 . 19066 in the direction he is moving, but its height is not affected. Thus, the height of the building is 110 m. keywords: 003 (part 1 of 1) 10 points An unidentified flying object (UFO) flashes across the night sky. A UFO enthusiast on the top of Pikes Peak determines that the length of the UFO is 90 . 5 m along the direction of motion. If the UFO is moving with a speed of . 844 c, how long is the UFO according to its pilot? Correct answer: 168 . 735 m. Explanation: = 1 r 1- v 2 c 2 = 1 p 1- (0 . 844) 2 = 1 . 86448 . Thelengthmeasuredbyanobserverinmotion relative to the ship = 90 . 5 m = L . The length measured by pilot (at rest to ship) is = L = (1 . 86448)(90 . 5 m) = 168 . 735 m . keywords: 004 (part 1 of 2) 10 points The proper mean lifetime of a subnuclear par- ticle called a muon is 2 s. Muons in a beam are traveling at 0 . 889 c relative to a labora- tory. The speed of light is 2 . 998 10 8 m / s....
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