I was wondering, from where does the opposite force and thus energy comes from when we apply force.
For example, lets say there are two persons (P1 and P2) on the universe, and no force is applied to them. P1 applies a force to P2. P2 will start to move. P1 lost some energy to do that. Now, according to the third law of newton, P1 will also get a force from P2 as a reaction.
But from who does the energy of reaction comes from? I mean, I found it hard to believe that P2 is the one who losses energy, just for the sake of reaction. So, from where does this force, and thus energy, comes from?
I am not an expert, I just know the basics. So please, be tolerant :P