A train consists of a caboose (mass = 1000 kg), a car (mass = 2000 kg), and an engine car (mass = 2000 kg). If the train has an acceleration of 3.

A train consists of a caboose (mass = 1000 kg), a car (mass = 2000 kg), and an engine car (mass = 2000 kg). If the train has an acceleration of 3.6 ms-2, then the tension force in the coupling between the middle car and the engine car is