What the question mean by "constant frictional resistance" in terms of formula?
I suppose they meant... "resistance force (f)" which is, >> f = m * a. So, here is my try...
m = 1.15 ton or 1150 kg
vi = 20 m/s
vf = 0
d = 800 m
v^2 - u^2 = 2ad
0 - 20^2 = 2a* 800
- 400 = 2a* 800
- 400 /...