Rough mass of wire (including insulation):
WD = wire density = 17.5x10^3 kg/m^3
m = WD * length * cross-sectional area
Friction of vehicle:
Fvc = coefficient of vehicle friction = 0.07 (no units)
F = Fvc * mass * g
where g = 9.8 m/s^2 (the acceleration of gravity)
Friction of dragging wire:
Fwc = coefficient of wire friction = 0.25 (no units)
F = Fwc * mass * g
Resistance of stranded wire:
See Wire Gauge Table.
Average precentage of wire length being dragged:
You figure it out!