I have two ideas (manuscripts) that I am working on, both in the field of physics.
The first is theoretical, mathy and generalized. It is steered toward computer vision. Probably if finished, would be published in a multidisciplinary journal for physics and computer science.
The second is a mix between theoretical physics and experimental physics. It is steered toward astronomical physics only. It applies one of the results found in the first manuscript.
Is it ethical to submit these two papers separately? How can I cite the papers if they are both under peer review?
Note: The two manuscripts do not hold the same goal and do not have identical results. If I am going to put a percentage on how much 2# uses from 1#, I would put 20%. Further, if I would put a percentage on how much different 2# from 1#, I would put 90%.