A tractor of mass 1000 kg tows a trailer of mass 1000kg . The total resistance is 4000 N and is constant . One quarter of the total resistance acts on the trailer . Initially the acceleration of both the tractor and trailer is 2.0 m/s^2 . Finally , both of them move with the same uniform speed of 6.0 m/s . What is the force on the tractor along the tow-bar when
(a) acceleration is 2.0 m/s^2
(b) the tractor and trailer move at 6.0 m/s
I need some explaination here . THanks .