I'm not sure what this question is going for? You can apply Newton's 3rd in all of these cases to talk about different things. Is there a more specific part to this question or does it want examples of how Newton's 3rd might be used for each possibility?For application of newton's third law, we mostly applied it in concrete objects. But can it be applied when it is
(3) Fluid which fills up the whole container?
If I am understanding you correctly I think what we have is a question about "contact forces."Yes, I would like to know some example of application of newton's third law for fluids. Meanwhile, when newton's third law cannot be applied.
And sometimes for fluids, it would be compressed and it may flow around. Compressibility of fluids won'r affect the application of newton's third law,right?
If I were in vacuum waving my hands, would there be an reaction force that I would experience like that in air?
If not, does it mean that newton's third law requires existence of "something" but there is no such "thing" in vacuum? What about antimatter, would it be considered as a the "thing" for Newton's third law to be applied?