Mechanics forces question 2Watch
So say you have a phone resting on a table then usually in problems we would combine their mass and look at the force of gravity on that combined mass.
But is it also correct to start off with the phone consider the force of gravity on the phone, notice it is not accelerating so there must be a normal reaction force from the table on the phone, then notice that this must have a reaction force which is the force of the phone on the table.
Then if you look on the table, you have its weight and the force of the phone on the table (and the normal reaction from the floor). Is this just a long way of combining the mass of the phone and the table and looking at their weight? Or are my forces just not correct?
I would say this is more of a physics question, maybe try posting there