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 question

  1. Aug 22, 2005 #1
    How would you make the first move in this type of question:

    Dick and Jane are twins. Dick goes off on a space voyage at a speed of 0.8c to a star 20 light-years away, while Jane stays behind on Earth. Dick and Jane each send out a radio signal once a year while Dick is away. How many signals does Dick receive? How many does Jane receive?
  2. jcsd
  3. Aug 22, 2005 #2
    First off, is the star 20 light years away according to Jane's reference frame or Dick's? Secondly, after how long and according to whose frame do they count up the signals? Anyway, they should both count the same number of signals.
  4. Aug 26, 2005 #3
    hmm... you're right~
    wow! you ask some pretty good questions~
  5. Aug 26, 2005 #4
    that's getting hard to analyze...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook