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: Ratio Problem Dealing with Radius and Centripetal Acceleration

  1. Mar 1, 2012 #1
    1. The problem statement, all variables and given/known data

    Two identical satellites orbit the earth in stable orbits. One satellite orbits with a speed v at a distance r from the center of the earth. The second satellite travels at a speed that is less than v . At what distance from the center of the earth does the second satellite orbit?

    2. Relevant equations
    a = (v)^2/r
    F = m/a
    F = G (M * m )/ r^2

    3. The attempt at a solution

    I'm really confused on how to manipulate these equations.

    Ultimately, I need to find an equation that relates "r" to "v."
    r = a * v^2
    So if the second satellite is moving slower doesn't that mean "r" has to be bigger? This makes me think of one of Kepler's Laws.
  2. jcsd
  3. Mar 1, 2012 #2
    That should read F=ma or a=F/m

    What does satellites orbit the earth in stable orbits tell you about the system?
    I'm not sure you understand what you're actually doing when you're working with these equations
  4. Mar 1, 2012 #3
    Wow. That was really careless of me. When it comes to problems like these, I don't understand how to do them well. Stable orbits = equal gravitational force?
  5. Mar 1, 2012 #4
    What should the gravitational force equal?

    What does it mean if the orbit is stable?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook