1115_Physics ProblemsTechnical Physics

1115_Physics ProblemsTechnical Physics - 456 P39.69...

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456 Relativity P39.69 (a) At any speed, the momentum of the particle is given by pm u mu uc == γ 1 2 bg . Since Fq E dp dt : qE d dt mu u c =− F H G I K J L N M M O Q P P 1 2 2 12 qE m u c du dt mu u c u c du dt F H G I K J +− F H G I K J F H G I K J −− 1 1 2 1 2 2 2 2 2 32 2 . So qE m du dt uc uc = −+ L N M M M O Q P P P 1 1 22 22 22 ej and a du dt qE m u c F H G I K J 1 2 2 . (b) For u small compared to c , the relativistic expression reduces to the classical a qE m = . As u approaches c , the acceleration approaches zero, so that the object can never reach the speed of light. (c) du qE m dt u t t 1 00 = zz = u qEct mc qEt = + 2 22 xu d t q E c tdt tt + 0 0 x c qE m c =+ F H I K P39.70 (a) An observer at rest relative to the mirror sees the light travel a distance Dd x 2 , where xv t S = is the distance the ship moves toward the mirror in time t S . Since this observer agrees that the speed of light is c , the time for it to travel distance D is t D c dv t c S S 2 t d cv S = + 2 . (b) The observer in the rocket measures a length-contracted initial distance to the mirror of
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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