What is the maximum order?

3 is the answer to this question. There are a lot of people who may find physics even more confusing as compared to math. There are just so many things that are hard to understand, especially in the beginning. To understand physics better, you can start with the basics first.

The more that you know the basics, the more that you can try solving more complicated physics questions. The more that you practice, the more that you will understand what you should do. With proper research and understanding, you are bound to know how you can solve more complicated physics questions in the long run.