Joe Smartie is 41 years old and has a son who is 18 years old. Joe leaves on a spaceship and takes a 30-year (spaceship time) round-trip at 0.960c. It is assumed that the spaceship quickly turns around after arriving at the destination and immediately comes back at the same speed. His son stays on Earth. How old will Joe's son be when Joe returns to Earth?
How do I do this? :O
How do I do this? :O
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You must use the lorentz factor * the proper time of 30 years as elapsed onboard the ship
lorentz factor of 1/(1-v^2/c^2)^.5 = 3.5714
3.5714 * 30 years = 107.41 elapsed time for the son which means he's probably dead.
lorentz factor of 1/(1-v^2/c^2)^.5 = 3.5714
3.5714 * 30 years = 107.41 elapsed time for the son which means he's probably dead.
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The easiest way to do it is time dilation.
t' = change in time relative to people on space ship
t = change of time relative to people on earth
t = t'/sqrt(1 - ((u^2)/(c^2)))
plugging in the variables you get
t = 30 / sqrt( 1 - (.960^2)) <== c's cancel
which yields
t = 107.143
Add that to the father's original age to get
148 years old
t' = change in time relative to people on space ship
t = change of time relative to people on earth
t = t'/sqrt(1 - ((u^2)/(c^2)))
plugging in the variables you get
t = 30 / sqrt( 1 - (.960^2)) <== c's cancel
which yields
t = 107.143
Add that to the father's original age to get
148 years old