What is the Coulomb potential energy of splitting uranium nuclei?

[v_pino]

Homework Statement

A uranium nucleus (X=92) splits into two equal fragments, and each has a radius of approximately 8x10^-15m. What is the Coulomb potential energy of such fragments when in contact?

Homework Equations

I tried using the coulomb law but that doesn't work. Could it be to do with binding energy?

The Attempt at a Solution

I know that the separation r will be twice the radius. But I don't know the charge on each atom. I tried saying that the charge on each is 46e, but I don't think that's right. I can't even get the right order of magnitude with Coulomb law.

The answer should be 3.05 × 10^−11 J.

 

[Klockan3]

Homework Equations

I tried using the coulomb law but that doesn't work. Could it be to do with binding energy?

They most likely want you to calculate as if they were two charged balls in contact. Ie you need to include the binding energy of each of the balls, yes.

 

[Dick]

Homework Statement

A uranium nucleus (X=92) splits into two equal fragments, and each has a radius of approximately 8x10^-15m. What is the Coulomb potential energy of such fragments when in contact?

Homework Equations

I tried using the coulomb law but that doesn't work. Could it be to do with binding energy?

The Attempt at a Solution

I know that the separation r will be twice the radius. But I don't know the charge on each atom. I tried saying that the charge on each is 46e, but I don't think that's right. I can't even get the right order of magnitude with Coulomb law.

The answer should be 3.05 × 10^−11 J.

I think everything you said you did is right. If I work it out I get 3.05 × 10^−11 J. What you didn't do right must be in what you didn't tell us. Can you show us the details?

 

[v_pino]

Thanks for the reply. I've upload a pdf file of my working since I don't know how to type in latex.

 

[Klockan3]

Thanks for the reply. I've upload a pdf file of my working since I don't know how to type in latex.

Ah, it is as simple as that you forgot that both sides need to have a charge of 46e, right now you are calculating as if one is 46e and the other is just a single e.

 

[v_pino]

Got it! Thanks!