posted by Anonymous .
A car is heading northwest at 80 km/h and a truck is heading east at 60 km/h. Determine the velocity of the truck relative to the car.
Vrel = Vtruck - Vcar
That must be treated as a vector equation. Break it up into x (east) and y (north) components.
Vrel,x = 60 -80 sin45 = 3.4 km/h
Vrel,y = 0 - 80 cos 45 = -56.6 km/h