A child causes a wagon to accelerate by pulling it with a horizontal force. newton's third law says that the wagon exerts an equal and opposite force on the child. how can the wagon accelerate? (hint: draw a free-body diagram for each object.)

Newton's first law of motion - sometimes referred to as the law of inertia. An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. it is first law that describes the situation, there is force that is by pulling the wagon which results to the motion of the wagon