Lazydog and his tractor (1330 kg) are pulling a trailer (530 kg) up a 7° hill. The trailer wheels roll freely. What is the magnitude of the force in the coupling between the tractor and trailer when their velocity is 8.7 m/s up the hill and they are slowing down at a rate of 0.2 m/s2? (N)

Answer 1

The mass of the tractor is irrelevant.
The mass of the trailer, m = 530kg
The inclination, θ = 7°

The net downward force is due to gravity, equal to

F1=mg sin(θ)

The coupling pulls the trailer with a force (tension) of T such that the net force is downwards equal to
F1-T=m(0.2)

Substituting F1, and solving for T
T=F1-m(0.2)
=mg sin(θ)- m(0.2)

Answer 2

thanks a lot