Newton's Third Law of motion says that every time that an object exerts a force on another object the second object exerts a force on the first that is equal in size and opposite in direction. When the marbles hit the box they are exerting a force on it. The box then deflects the marbles, and applies the same force to the marbles as the marbles originally did to the box. The forces that are exhibited here are contact force and friction. The contact force is between the box and the marbles. This slows the marbles down. Friction between the track and the marbles also slows its acceleration.
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