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!

How to solve planet orbital question

  1. Oct 8, 2008 #1
    Ok I remeber a question on my physics test. where theres a planet orbiting a star in some other solar system.

    heres what was given to me.
    the radius,and the time it took for it to finish 1 revolution. I was asked to find the mass of the sun, that the planet was orbiting around

    so heres what i did.

    I calculated the distance, which was 2 pi r.

    I divided that value by time and got the speed.

    then i used Fc=FG formula.
    mv^2/r = Gm1m2/r^2

    with some cancellations, im left with
    v^2=Gm(star)/r

    so i just isolated for m and solved it. I remember i got like some number x 10^30kg.

    but did i do this question right? was this the right method of solving it?
     
  2. jcsd
  3. Oct 8, 2008 #2

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    Sounds reasonable, the sun's mass is around 2^30 kg
     
  4. Oct 8, 2008 #3
    i asked my friend how he had solved it, and he said he used
    Fc=FG
    4pi^2mr/T^2 = Gm1m2/r^2

    does my method and his method work in this question?
     
  5. Oct 8, 2008 #4

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    It's the same thing, you can also use T = 2 [tex]\pi \sqrt{ ( r^3 / GM )}[/tex]
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: How to solve planet orbital question
  1. Orbiting of Planet (Replies: 13)

Loading...