ExamI2001 - 29:030 Physics IV Exam I February 16, 2001...

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29:030 Physics IV Exam I February 16, 2001 Closed book exam. Please show all work to get full credit. Point values for each problem are indicated. Please ask questions if you need clarification. If you don’t show your work, or make written comments, then there is no way for me to give partial credit. 1) (12 points) Recently a proton was detected that evidently hit the earth’s atmosphere with 10 20 eV of energy. The rest mass of the proton is such that mc 2 ~10 9 eV. a) If it came from the center of the galaxy (3x10 20 meters away) how long did it take to get here (in our frame of reference)? b) How long did it take to get here from the galactic center in its own frame? c) As viewed in the particle frame, how far is it from here to the galactic center? 2) (12 points) Consider the electrical charging of a spacecraft due to the photoelectric effect from light from the sun. When there are sunspots, the sun radiates a lot of short-wavelength light (x-rays) in addition to visible light. a) Is it conceivable that a spacecraft could have virtually no charging unless the x-rays
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This note was uploaded on 03/30/2008 for the course 029 030 taught by Professor Skiff during the Spring '08 term at University of Iowa.

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ExamI2001 - 29:030 Physics IV Exam I February 16, 2001...

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