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: Universal Gravity Circular Orbit

  1. Nov 7, 2012 #1
    1. The problem statement, all variables and given/known data
    What is the radius of a circular orbit about the earth where the acceleration is 0.1g?

    2. Relevant equations
    Radius of Earth= 6.38x103 km
    Mass of Earth= 5.98x10^24 m/s

    3. The attempt at a solution
    I said 1/(2^x)=1/10 then did log2(10)=x and solved for x getting 3.3 earth radiuses. I multiplied that by the radius of the earth and got 21,000 m. This was obviously the wrong method.
  2. jcsd
  3. Nov 8, 2012 #2
    Your method seems correct, but the equations seems all messed up (not sure why you use logs to the base 2?):
    r2 = 10 R2
    so that
    r = √10 R
    Your answer seems sligthly off.
    Also Halliday and Resnick lists R as 6.37 which then gives r as 20 x 106 m.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook