Problem Set #8 Physics 200 Due Wednesday Nov. 4, 2009 Read “Relativity Notes” on Classes site, p. 1 – 7. Pages 7 – 19 (starting w/ “Four Vectors”) is optional. 1) Two rockets of rest length L0 are approaching the earth from opposite directions at velocities (relative to the Earth) ± c /2 . How long does one rocket appear to the other? 2) The earth and sun are 8.3 light-minutes apart. Ignore their relative motion for this problem and assume they live in a single inertial frame, the Earth-Sun frame. Event A occurs at t = 0 on the earth, and event B at t = 2 minutes on the sun. Find the time difference between the events according to an observer moving at u = 0.8 c from Earth to Sun. Repeat if observer is moving in the opposite direction at u = 0.8 c . 3) Return to the Earth-Sun case above. What is the speed of a spacecraft that makes the trip from the Sun to the Earth (which is 8.2 light minutes) in 5 minutes according to the on board clocks? 4) A muon is an unstable particle with a lifetime of 2 x 10
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