An airport tug pulls two baggage trolleys. The tug is attached to the front trolley, and the rear trolley is connected to the front trolley by a rope. A student first treats both trolleys and the rope as one system, then considers the rear trolley alone. Which statement correctly describes the tension force in the rope for these two choices of system?
The tension is external to the system containing both trolleys and the rope, but internal to the system consisting of the rear trolley alone.
The tension is internal to both systems because the rope connects the trolleys.
The tension is external to both systems because the rope pulls on a trolley.
The tension is internal to the system containing both trolleys and the rope, but external to the system consisting of the rear trolley alone.