Newton 2nd law, forces and vectors

[roovid]

A car of mass 1000 kg tows a caravan of mass 600kg up a road which rises 1m vertically for every 20m its length.
There are constant frictional forces of 200N and 100N to the motion of the car and caravan respectively.
the combination has an acceleration of 1.2ms^-2 with the engine exerting a constant driving force.
Find a. the driving force
b. the tension in the tow bar

i have the sol'n for part a
no clue for part b
will post my progress below

 

[roovid]

part a
using g as 10

f = ma
(1000 + 600)(1.2)
1920NF component paralled to plane inclined
(1600)(10) Sin∅
(1600)(10)(1/20)
=800N

driving force
1920+800+200+100
=3020N
......

part b
1920 - 800
1120N

lol
oops

 

[ehild]

The force of the tow bar pulls the caravan. Find the resultant of all forces exerted on the caravan. You know its acceleration.

ehild