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: Determine the magnitude of and direction of the velocity

  1. Oct 9, 2007 #1
    I have problems on understanding Relativity.So can someone check this one.
    1. The problem statement, all variables and given/known data

    2. Relevant equations
    A spacecraft is launched from the surface of the with velocity of 0.600c at an angle of
    [tex]50^{\circle}[/tex] above the horizontal positive x axis.Another spacecraft is moving past,with a velocity of 0.700c in the negative x direction..Determine the magnitude of and direction of the velocity of the first spacecraft as measured by the pilot of the second spacecraft.

    3. The attempt at a solution
    [tex]v_{1x}=0.6c\times cos50^{\circle}[/tex]
    Last edited by a moderator: Jan 7, 2014
  2. jcsd
  3. Oct 9, 2007 #2


    User Avatar
    Gold Member

    the equation in the y direction is:
    other than this it looks good to me.
  4. Oct 9, 2007 #3
    Like this
  5. Oct 9, 2007 #4
    but should be there similar equation for [tex]v_{1x}[/tex] ?
  6. Oct 9, 2007 #5


    User Avatar
    Homework Helper

    I think it's best to use these equations:

    [tex]u_x' = \frac{u_x - v}{1-u_x v/c^2}[/tex]

    [tex]u_y' = \frac{u_y}{\gamma (1-u_x v/c^2)}[/tex]

    v is the velocity of the second ship... ie v = -0.700c, and ux' and uy' are the speeds measured by this second ship...

    just plug in ux, uy, v and gamma and you'll have the answers.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook