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Velocity with relativity

  1. May 13, 2009 #1
    Find the speed of a particle that takes 2.0 y longer than light to travel a distance of 6.7 ly. Answer is wanted in terms of 'c'.



    delta(t)= delta(t0)/(sqrt(1-(v/c)^2)).



    8.7= 1/(sqrt(1-(v/c)^2))-->
    1/8.7=sqrt(1-(v/c)^2-->[/b]
    (1/8.7)^2=1-(v/c)^2-->[/b]
    (v/c)^2=1-(1/8.7)^2-->[/b]
    v/c=sqrt(1-(1/8.7)^2)-->[/b]
    v/c=0.993372-->
    v=0.993372c....which is incorrect, any assistance would be greatly appreciated[/b]
    note: I also tried delta(t) to be 4.7...also incorrect
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 13, 2009 #2

    dx

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    What is the speed of light in units of light-years per year? It's just one! Light travels one light-year per year.

    The particle travels 6.7 light-years in (6.7 + 2) years, so it's speed in units of light-years per year is ... ?
     
  4. May 13, 2009 #3
    Thank you so much!! That makes perfect sense. I hate when I over-complicate problems like these. Much appreciated!
     
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