1. Not finding help here? Sign up for a free 30min 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!

Orbit Collision

  1. Oct 28, 2008 #1
    1. The problem statement, all variables and given/known data
    If Halley's comet hits the earth head on and after the collision the earth continues to move in its initial direction but with 12% greater speed, find the new semi-major and semi-minor axes on the new earth orbit in terms of the earth-sun distance (R) for the present circular orbit of the earth.

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Oct 28, 2008 #2
    Remember that the earth's angular momentum is conserved through its orbit.
    L = mvr

    And consider that, since the earth's new velocity is in the same direction as before, it would go back to R for its semi-minor axis, due to the fact that the new velocity is in a single coordinate only, and it therefore has no force pushing it tangentially from its original path - it only moves tangential relative to it's old path as it diverges from it due to higher speed.
  4. Oct 28, 2008 #3
    I don't necessarily agree with R remaining as the semi-minor axis because the origin of orbit(now an ellipse) isn't at the previous focus (being the sun). However, could R be given by a-c=R or (semi-major axis)-(distance from origin to focus)=R ?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?