TITLE: How to study motion?
QUESTION [0 upvotes]: I am a high school student and recently learned about linear, circular and oscillation motion. I also read that Newton laws of motion fails at quantum level.
Now, I am curious to know what is fundamental basis of motion that could be used at any level. Can we study all types of motion under single branch?

REPLY [2 votes]: It would not be very useful. We don't have a unified theory either. But even apart from this, It would be insane to use Quantum mechanics to describe the motion of Car.
The four main domain of physics shown below with their domain

The relativistic mechanics is approximated when $v/c<<1$ to classical mechanics. So it's better to use classical mechanics in this domain. We still don't have a unification of general relativity and Quantum mechanics. More on this can be found here.
{"set_name": "stack_exchange", "score": 0, "question_id": 643437}