1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Special Theory of Relativity question

Tags:
  1. Sep 4, 2012 #1
    1. The problem statement, all variables and given/known data
    I took this form Yale Open Course

    2. Relevant equations
    Special Relativity equations


    3. The attempt at a solution
    I will try to divided this problem into two parts: First one is - what is its location
    in my frame when it ticks 1 second in its frame?
    and second one - If it emits alight pulse at that time, at what time t^∗ according to me will that pulse reach my origin?.

    So for the first one i have x=? and that t'=1. I use the lorentz transformation for x point.
    x=(x' + ut')/SQRT(1-(u^2)/(c^2)). I am not sure that i can use this formula for this purpose
    but if i assume that x' is 0 i get x= ut'/SQRT(1-(u^2)/(c^2)) = 2.25 * 10^8 m
    Then i need to find t when light hits my origin ie t^* = t + t'' where t'' is time light takes to travel to my origin in my frame. Perhaps i can get t buy manipulating lornetz equation for t'. Since i have t' and x i can figure out t. t' = (t - (ux/c^2))/SQRT(1-(u^2)/(c^2)) ==>
    1 = (t - (ux/c^2))/0.8 ==> 0.8 + 0.45 = t = 1.25. So then i need to find t''. I have no idea to how to find t'' unless to plug int into standard v=s/t formula. If that's the case then c=x/t ==>
    t= 0.75 where x is 2.25 * 10^8 m which i found in first part of the problem. So t^* is 2.

    I have a feeling that i made a mistake somewhere, possibly at the beginning of the problem where i assumed that x= ut'/SQRT(1-(u^2)/(c^2)) and i am not sure if that's quite right.
     
  2. jcsd
  3. Sep 4, 2012 #2

    Janus

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Looks good to me.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Special Theory of Relativity question
Loading...