What is the difference between「ものなら」 and 「(の)なら」?

Question

I would like to understand the nuance between two sentences. I found on a website the sentence :

この問題{もんだい}を解{と}けるもんなら解いてみろ。 : If you can solve this problem then try solving it.

And I wondered what would the difference be if I just used 「なら」 without 「もの」 in a conversation for example :

この問題を解けるんなら解いてみろ。

I feel like the second sentence using 「のなら」 would be bad without context, but after reading one more time the first one it feels the same.

So what would the nuance be in these two sentences?

And do we use 「ものなら」 only after a potential verb?

In a sentence like :

お金持{かねも}ちに成{な}れるもんならこの仕事{しごと}を辞{や}めるよ。

Here, without context I don't think replacing the 「ものなら」 by 「なら」 is correct. Am I right?

Answer 1

When 「ものなら」 comes after a potential verb, the speaker thinks it is actually impossible.

この問題を解けるもんなら解いてみろ。

This is a provocative or insulting phrase because it implies "no, you can't".

お金持ちに成れるもんならこの仕事を辞めるよ。

The speaker doesn't think he can quit his job and wishes he could.

cf. http://dictionary.goo.ne.jp/leaf/jn2/219924/m0u/

Answer 2

I think the first has the nuance of "If (you think that) you're the kind of person who can solve this problem, then have a go at solving it."

The second has the nuance of "If you are going to solve this problem, then do solve it."