# Derivation Sanity Check.

1. Feb 27, 2010

### Topher925

I feel like an idiot asking this, but I need a check on a derivation. Can anyone verify this for me or let me know if its wrong?

1. The problem statement, all variables and given/known data

Expand the equation.

2. Relevant equations

0 = m$$\frac{d}{dr}$$($$\frac{1}{r}$$$$\frac{d}{dr}$$(ru))

3. The attempt at a solution

$$\frac{d2u}{dr2}$$+$$\frac{1}{r}$$$$\frac{du}{dr}$$-$$\frac{u}{r2}$$ = 0

or

u'' + u'/r - u/r2 = 0

2. Feb 27, 2010

### tiny-tim

Hi Topher925!

Yes, that's fine.

3. Feb 27, 2010

### Topher925

Crap. I was afraid someone was gonna say that.