Written here are net forces acting on a body. But I am having difficulty in understand them after reading from textbook and online material.
In the book, we have been introduced to thrust.
It clearly says that pressure exerted by a body on the surface = weight of the body.
Then, why is it not that $mg$ is nothing but $P_1A$ and $P_2A$?
Can we also say that it is $F = ma$ expression (the first equation as a whole) where $a = 0$?