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: Time dilation and spacecraft

  1. Oct 7, 2006 #1
    hey i just need a lil help with this question

    An alien spacecraft is flying overhead at a great distance as you stand in your backyard. Yyou see a bright signal light in the spaceship blink on for 190.0 ms. The commander of the spacecraft measures that the signal is on for 12.0 ms.

    what is the speed of the spacecraft relative to the earth?

    i calculated the speed and it comes out to be greater than the speed of light, which is impossible. just wondering if i had calculated it wrong or maybe someone has a better explaination!

  2. jcsd
  3. Oct 7, 2006 #2


    User Avatar

    Staff: Mentor

    Show your work and someone will probably be able to tell you where you went wrong. Otherwise we can only guess!
  4. Oct 7, 2006 #3
    i worked it out, just a simple miscalculation.

  5. Oct 7, 2006 #4
    you should get ...


    So that's a fast vessel.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook