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!

Gravitaional Potential Energy help, please

  1. Nov 20, 2012 #1
    1. The problem statement, all variables and given/known data
    Four uniform spheres, with masses mA = 350 kg, mB = 600 kg, mC = 1500 kg, and mD = 300 kg, have (x, y) coordinates of (0, 50 cm), (0, 0), (-80 cm, 0), and (40 cm, 0), respectively. Sphere A is then removed.
    (a) Calculate the gravitational potential energy of the remaining three-particle system.



    2. Relevant equations
    U=-Gm1m2/r12-Gm1m3/r13-...


    3. The attempt at a solution
    U=-G(McMd/Rcd+McMb/Rcb+MbMd/Rbd)
    U=-G(1500*300/.12+1500*600/.8+600*300/.4)=-3.55e-4 J
    It's telling me this is wrong but I can't see where I'm going wrong. Thanks in advance.
     
    Last edited: Nov 20, 2012
  2. jcsd
  3. Nov 20, 2012 #2
    Nevermind. I found my small error. Thanks, anyway.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook