I am wondering if I can obtain a german passport. My father was born in german in 1947. I was born in australia and hold a Australian passport. My fathers mother born in poland.

Generally, you have to be a national of the country in order to get their passport, you are an Australian national, so you get an Australian passport.

Nationality can be decided on blood line, but since you only have one generation of german in your family, I suspect that this is not the case.
It can also be decided by where you are born: in your case Australia.

If you are desperate, you can try to gain nationality in Germany through naturalization (http://en.wikipedia.org/wiki/Naturalization).

Do you live in Germany currently?