1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Spacetime Diagram

  1. Sep 16, 2013 #1
    1. The problem statement, all variables and given/known data
    At time t = 0, a spaceship leaves Cape
    Canaveral (x = 0) at speed 2/3c, heading
    directly upwards (+x direction) toward a
    satellite in orbit. The satellite is located a
    distance 2 AU (see footnote2 if you forget
    what that is) above the earth’s surface.
    When the ship reaches the satellite, it
    engages its Magic Hyperdrive to instantly
    reverse course, and head back toward Cape
    Canaveral at speed 1/3c.

    Plot the worldlines of the ship and of Cape
    Canaveral itself, both as seen from Cape

    3. The attempt at a solution

    My question is primarily for the "instant reversal" of the ship. I believe that the world line for Cape Canaveral will be exactly vertical and the ship will have a straight line with a slope of 3/2 terminating at x=2. At x=2 it goes in reverse but I'm not sure how this would look in the Cape's frame. Will the line of the ship then go left with a slope of -3/1 until it intersects with the Cape's vertical line? Or is there some other path?

    Also, if anyone knows of a website or downloadable pdf that has example problems of these types of problems I'd love to see it/them.

    Thanks for the help.
  2. jcsd
  3. Sep 17, 2013 #2


    User Avatar
    Homework Helper

    yep. That sounds right to me. and sorry, I don't know of any websites like that. Maybe there is something useful in the math & science learning materials section of physicsforums.

    edit: be careful with the units that you are using though. when you say x=2, there should be units with this.
  4. Sep 17, 2013 #3
    Thank you, for all of our problems we're using arbitrary units.

    Thanks again for the help.
  5. Sep 18, 2013 #4


    User Avatar
    Homework Helper

    ah cool. No worries :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted