What is the change in velocity if the initial velocity vector is 3 m/s to the east, and the final velocity vector is 3 m/s to the south?

4.2 m/s to the southwest

The change of velocity is equal to the final velocity subtracted by the initial velocity, which is equal to the final velocity add the negative initial velocity. We can calculate the change using the Pythagorean theorem The direction is southwest as shown in the graph.