## About Mass (3)

How about the second law of motion in its complete form?

The complete form of F=ma is:

Putting it into two reference frames, it becomes:

Under Special Relativity, this is the final form, as nothing can be simplified.

As mass is a constant in the Newtonian system, we can move it out, so the complete form becomes the normal form:

So our aforementioned conclusion still holds.