Physics is about understanding the principles of nature and it's application - although the later is my interpretation and some colleges would disagree with it 🙂
As a physicist, sometimes you have to be more of an engineers than scientists and we are more stuck on solving technical problems in order to produce new insights in science. And that's what makes us physicists special. Because we constantly have to deal with problems, we have become ideal problem solvers.
But of course, that's just my humble opinion, and I could be wrong.
That's one of my favourite application of my physics knowledge. It's about to make some approximations based on a limited knowledge of the underlying problem and trying to solve it quick and dirty. It turns out, that this approach is not too far away from reality, if you make the steps clever.
The original Fermi-Problem was suggested by Enrico Fermi to his students: "How many piano tuners are there in Chicago?".
It turns out, that with some rough qualitative approximations you come to the solution within one order of magnitude on the fly without direct knowledge of the actual data. It's just like a detective, you collect the evidence that you have now on the spot and try to make some approximations that lead to an approximate solution, that, based on the quality of your assumptions, are not too far away from the real solutions. "It's for a good thing, Doctor Watson!"
Since I think they are mostly Fermi-Problems I link the what-if xkcd page of Randall Munroe. Very funny, yet instructional. Enjoy 🙂