Hi, I'm currently learning how to solve two body problems and I'm having a little trouble with that. My question regards a certain example I found in The Physics Classroom web site that goes like this: "A 5.0-kg and a 10.0-kg box are touching each other. A 45.0-N horizontal force is applied to the 5.0-kg box in order to accelerate both boxes across the floor. Ignore friction forces and determine the acceleration of the boxes and the force acting between the boxes." I managed to find out the acceleration(3 m/s/s) but I don't understand how to find the force acting between the boxes. In the solution of this example they took the 10 kg boy and just calculated it's net force(30 N) and I undertood that but if I to calculate the net force acting on the 5 kg(15 N) body I'll get a different result entirly. How can I determine the force acting between the boxes using the 5 kg box alone. Thanks!