[Stickyelmo]

Hi peeps I don't understand what I did wrong for this question. I think I may have the first part wrong too and got it right by luck.



Hope it isnt a problem doing most of this on paint :0

[yclicc]

(i)

Car and trailer constant speed i.e. Driving force = resistance force, acceleration =0.

Just look at the trailer.

Forces acting=T-400
Acceleration=0 so no net force, so T=400N (a tension)

(ii)
Look at trailer again.
Acceleration = 0.6(m/s)/s
Mass=500
Forces=T-400

Use F=ma (Newton 2 or N II)
T-400=500*0.6
so T=700N (tension)

The important result is the acceleration of the car/trailer individually is the same as that of the whole system, so just consider the trailer. The car is irrelevant here.

To get driving force consider just just car using tension u just calculated.