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Understanding geometry problem in relativity

  1. Aug 3, 2017 #1
    1. The problem statement, all variables and given/known data
    It is not ordinary problem, it is connected to it. I don't understand a figure and how is described. The problem is here http://www.pmaweb.caltech.edu/Courses/ph136/yr2011/1102.2.K.pdf How did equation 2.4 from figure 2.3 arise? Why disappear ##\Delta t^2## from the right?
    Another question is: In the text above eq.2.4 is written ##c\Delta t^2=\Delta t^2##?? Ok, if it says work in geometric units where ##c=1## ok, but it isn't mentioned.

    2. Relevant equations
    eq 2.4 ##\Delta s^2=-\Delta t^2+\Delta x^2+\Delta y^2=-(2h-\Delta y^2)+\Delta y^2##

    3. The attempt at a solution
    An attempt occurred in my mind, when I thought about it half an hour :-)

    Thank you all.
  2. jcsd
  3. Aug 3, 2017 #2


    Staff: Mentor

    So you figured it out?
  4. Aug 3, 2017 #3
    No, second equality in 2.4 is out of me. ##-\Delta t^2+\Delta x^2+\Delta y^2=-(2h-\Delta y)^2 + \Delta y^2##
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