Answer:
40 m/s due north
Step-by-step explanation:
Consider that the south direction a negative Y axis and north direction as + Y axis
v1 = 20 m/s South = 20 (-j) m/s
v2 = 20 m/s North = 20 j m/s
Change in velocity = v2 - v1 = 20 j - 20 (-j) = 40 j m/s
So, change in velocity is 40 m/s due north.