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: Satelite orbit distance

  1. Sep 21, 2012 #1
    1. The problem statement, all variables and given/known data
    A 320kg satellite experiences a gravitational force 800N. What is the radius of the satellite's orbit?

    2. Relevant equations
    G m1m2 / d^2

    3. The attempt at a solution
    I started with

    800N = (G(320kg)(5.98(10^24)kg) / d^2

    After some algebra and rounding I ended up with d = 40,000 km. Is that reasonable?
  2. jcsd
  3. Sep 21, 2012 #2
    when I put 40,000 km into the original equation and solve for the force I get around 79.77N

    what value did you use for G?
  4. Sep 21, 2012 #3
    I think the standard for any calculations in classical mechanics is kg and meters. So perhaps if you try 40,000,000m.

    I used 6.67 x 10 ^-11 for G.
  5. Sep 22, 2012 #4
    Shameless bump. Still need help.
  6. Sep 22, 2012 #5
    I kept trying again and again but I am getting 12k kilometers

    [itex]d = \sqrt{\frac{GMm}{F}}[/itex]



    [itex]d = \sqrt{\frac{(6.67*10^{-11}N*(\frac{m^{2}}{kg^{2}}))(5.98*10^{24}kg)(320kg)}{800 N}} = 1.26*10^{7} m[/itex]

    maybe you can point out where our calculations differ? I might be doing something hilariously incorrect.
  7. Sep 22, 2012 #6
    No, you're right. I re-did the calculation again and paid proper attention to parenthesis this time. I'm just not calculator savvy at all.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook