(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A) How much work would it take to push two protons very slowly from a separation of 2.00*10^{-10}m (a typical atomic distance) to 3.00*10^{-15}m (a typical nuclear distance)?

B) If the protons are both released from rest at the closer distance in part A, how fast are they moving when they reach their original separation?

2. Relevant equations

Eq 1: K_{a}+ U_{a}= K_{b}+ U_{b}

Eq 2: W_{a->b}= U_{a}- U_{b}

3. The attempt at a solution

Using Eq 1: to solve for v_{b}:

0 + U_{a}- U_{b}= (1/2)mv_{b}^{2}

sqrt( 2(U_{a}- U_{b})/m ) = v_{b}

Where m = 1.67*10^{-27}kg, the mass of a proton.

From here, I plug in values and get v_{b}= 9.58598*10^{6}m/s.

Naturally, this is wrong.

I think the error is in that I worked the problem as though one of the protons is held still (which I'm sure is fine for part A, but apparently not B). If this is the case, how should I be handling this problem?

Edit: Whoops. Forgot to re-add this in when my first thread submission attempt got fried...

I've already calculated W_{a->b}= 7.6729*10^{-14}J. This, according to the homework problem, is correct.

Edit2: Epic fail. Accidentally posted in the wrong section. This should go under Introductory Physics, as it's just introducing calculus-based physics. If someone could move this thread to there, that would be appreciated.

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# Homework Help: A problem with electric potential and conservation of energy

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