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: Find typical energy of nuclei in solar core

  1. May 7, 2012 #1
    1. The problem statement, all variables and given/known data

    Calculate the typical energy of nuclei in solar core. Calculate thermal energy required for a proton to overcome the Coulomb barrier and get within range of strong nuclear force (10^-15m)

    2. Relevant equations

    None given

    3. The attempt at a solution

    I have the core temp as 1.5 x 10^6 K. I know that typical nuclei will have mass mp which is 1.67 x 10^-27kg.

    I am sure there must be a simple equation to work this out, but I've never come across it before! I know that the point of the question is to illustrate that fusion reactions would not occur at this temp without quantum tunneling. (Eg typical thermal energy is NOT enough to overcome Coulomb barrier.)
  2. jcsd
  3. May 7, 2012 #2
    A cup of tea and a browse of wikipedia has led me to the following attempt:

    Typical energy = 3/2 kbT = 3.1 x 10-17J

    Coulomb repulsion barrier energy = ke2/r = 2.3 x 10-13J

    Rearrange the first formula to find that the temperature required to break the Couloumb barrier is approx 10^10K.

    Is that the correct approach? (Feel embarrassed about posting this now, I knew it would be simple!)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook