Any reason you don’t want to use the 2D physics blocks? They are actually awesome and can do amazing things for you with very few code blocks. For example, the water simulator only uses 22 blocks:
https://play.creaticode.com/projects/78337eed686831330f3879a0
If you have a more specific question on how to do something with the 2D physics engine, we can give you some example code.
CreatiCode