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: Help, Rotational Motion

  1. Jan 14, 2008 #1


    User Avatar
    Gold Member

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

    Calculate the centripetal acceleration of the Earth in its orbit around the sun and the net force exerted on the Earth. What exerts this force on the Earth? Assume that the Earth's orbit is a circle of radius (r) 1.5 * 10^11 m.

    2. Relevant equations

    Centripetal acceleration = (v^2)/r = ((4)(pi^2)(r))/(t^2)

    Centipetal Force = ((m)(v^2))/r

    3. The attempt at a solution

    Centripetal acceleration = ((4)(pi^2)(1.5 * 10^11 m))/(31536000^2 s^2) = .006 (m)/(s^2)

    I'm ok with the centripetal acceleration but I don't know how to find the average net force without the mass. The centripetal force in this case is the gravitational force of the sun pulling on the Earth. Can someone please give me an idea on how to solve this problem? Thanks.
  2. jcsd
  3. Jan 14, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    You do need the mass of the earth to compute the force. Since they didn't give it to you, you'll have to look it up.
  4. Jan 15, 2008 #3


    User Avatar
    Gold Member

    All right. Thanks.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook