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: Gravitational Force Between Planets

  1. Oct 4, 2009 #1
    1. The problem statement, all variables and given/known data
    Part 1)
    The centers of a 21.2 kg lead ball and a 442 g lead ball are separated by 10.38 cm. What gravitational force does each exert on the other?

    Part 2)
    What is the ratio of this gravitational force to the weight of the 442 g ball?

    3. The attempt at a solution

    I found part 1 - 5.8 X 10^-8 N by using the formula Gm1m2/r^2.
    Part 2 I haven't the slightest idea. Does anyone know how to find the ratio?

    Thanks in advance.
  2. jcsd
  3. Oct 4, 2009 #2
    To find a ratio of gravitational force to the weight of the 442 g ball, it is simply the gravitational force divided by the weight of the ball.
  4. Oct 4, 2009 #3
    So simple and yet I couldn't get it! Thank you.
  5. Oct 4, 2009 #4


    User Avatar
    Science Advisor
    Gold Member

    remember to convert 442g, a mass, into a weight in Newtons (on Earth I presume).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook