A steamer is moving due east with 36 km/h. To a man is the steamer the wind appears to blow at 18 km/h due north. Find the velocity of the wind.

Vwx=Vw−Vs⇒  (Vwxi^+Vwyj^)−  10i^−5j^ Or   (Vwxi^+Vwyj^)=5j^+10j^ |Vw|=  55  tanθ=  12    or θ  =  300  I.e. wind is blowing at 55  ms−1300  North of east.