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Applications of Special Relativity


Problems on the Twin Paradox

Problem : A spacecraft travels at 0.99c to a star 3.787×1013 kilometers away. How long will a roundtrip to this star take from the point of view of someone on the earth?


Problem : With reference to the previous problem, how long will the roundtrip take for someone in the spaceship, according to someone measuring from the earth?


Problem : Now in the reference frame of someone in the spaceship, what is the time taken for the roundtrip as observed by a passenger, and by someone on earth (ignoring the times when the spaceship is accelerating or decelerating).


Problem : If one person stays on earth and one person travels to the distant star, who will age more during the trip and by what amount?


Problem : Twin A floats freely in outer space. Twin B flies past in a spaceship at speed v 0 . Just as they pass each other they both start timers at t = 0 . At the instant of passing B also turns on his engines so as to decelerate at g . This causes B to slow down and eventually to stop and accelerate back towards A so that when the twins pass each other again B is traveling at speed v 0 again. If they compare their clocks, who is younger?