Question

You have learned that Newton's 3rd Law states that when one mass exerts a force on another mass, there will be equal but opposite forces between then. If you recall, this is what allows us to jump UP off the ground, even though we press DOWN with our legs into the Earth. But... what about the following scenario? A tractor is hooked to a trailer full of horses. Once the tractor begins pulling the trailer forward on a level surface, the trailer will necessarily pull back on the tractor with an equal force. Your task: Answer why this system is able to move at all. (Obviously, it will... but why and how can it given the physics you have learned thus far?)

Answer 1

the Newton's 3rd law of motion states that the every action their is an equal and opposite reaction.

But when you apply acceleration to the tractor it will move forward and due to this trailor also moves because the force is proportional to the acceleration and tractor have acceleration and trailor just at a rest so it's will move.

I think this is the physics used their.