# Does an action-reaction pair always contain the same kind of force? Tags: newtonian-mechanics, forces - Score: 22 - Views: 8841 - Answers: 8 - Answered: yes - Asked by: Siddhartha (918 rep) - Asked: 2019-12-01 - Edited: 2019-12-01 - Site: physics ## Question According to Newton's third law, the forces in an action-reaction pair must have the same magnitude and opposite directions. But do they have to be the same kind of force (gravitational, electromagnetic, strong, weak)? ## Answers ### Answer by Andrew Kay (score: 20 [ACCEPTED]) We're talking about the "two sides" of the SAME force, so it must be yes, they are of the same type. For example, if I attract you gravitationally, then you are also attracting me gravitationally. There is only one physical source of the force (in this case, gravity) and it is pulling us both equally and oppositely. Since there's only one thing, it has, and can only have, one type. Or, to put it another way, according to Newton's third law: When I push against you, you are also pushing me back. It is the same physical thing doing both pushes, in this case electrical repulsion of our atoms. Or like this: Imaging I support a book of 1N weight i