A 1.2x10^4-kg truck is travelling south at 22m/s. What net force is required to bring the truck to a stop at 330 m? What is the cause of this net force?

Answer 1

Wouldnt it normally be a braking force?

Vf^2=Vi^2+2ad= Vi^2+2(Force/mass)d
where force and d are in the same direction, it should work out to be negative.