Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Relativity problem.

  1. Dec 19, 2004 #1
    In a particular reference frame, two events occur 100m apart, with an intervening time interval of 0.30us . The speed of a reference frame in which they occur simultaneously is ?

    anyone can tell me how to slove this problem? I dont have any idea about it . Thanx
  2. jcsd
  3. Dec 19, 2004 #2
    you need to find a frame of reference where the time interval between events becomes zero.
  4. Dec 19, 2004 #3

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    Let the occurence of event A have coordinates (x,y,z,t) = (0,0,0,0) in this frame, f. Event B will have coordinates (x_B,y_B,z_B,t_B) = (100,0,0,.30) (times in us.)

    Consider another frame of reference, f', moving parallel to the direction of the displacement between Event A and Event B with speed v and with its origin at Event A (i.e in this frame the coordinates of Event A are (x',y',z',t') = (0,0,0,0))

    We want to set v so that the coordinates of Event B in f' are [itex](x'_B,y'_B,z'_B,t'_B) = (x'_B,0,0,0)[/itex]

    Times and distances in these frames are related by the Lorentz transformation:

    (1)[tex]t'_B = \gamma (t_B - vx_B/c^2)[/tex]
    (2)[tex]x'_B = \gamma (x_B - vt)[/tex]

    So determine v if:
    [tex]t_B' = 0[/tex]

    Last edited: Dec 19, 2004
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook