Hi, I am a little confused with the concept of action reaction pair of forces. Does this depend on mass? For example, if a train engine is pulling a buggy with force F, what would be the force applied by the buggy on the engine? The masses of the two are different and there is force of friction on the buggy. I know that for 2 forces to be action reaction pair, they have to act on different objects. Does this mean that the force the buggy applies on the train engine is also F (in magnitude), but since mass is different, the acceleration would vary? I am not sure if I fully understand the concept.