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: Orbital Potential Energy to find r and phi in terms of t.

  1. Oct 31, 2016 #1
    1. The problem statement, all variables and given/known data
    A particle in central force feild has the orbit r=cφ^2, c is a constant. Find the potential energy, Find r and phi in terms of t.
    I get how to find the potential energy and found it to be U=-l^2/mu (2c/r^3+l/2r^2)
    l is angular momentum and mu is the reduced mass
    But how do I get r and phi in terms of t after this?

    2. Relevant equations
    From what my professor showed in class l=mu r^2 dφ/dt was important
    he used that to integrate and get r^2(t)=lt/mu
    I'm trying to use this method to get r and phi

    Any help is much appreciated, thanks!
  2. jcsd
  3. Oct 31, 2016 #2


    User Avatar
    2017 Award

    Staff: Mentor

    Sounds good. Once you have dφ/dt, you can get dt/dφ and integrate.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted