Question

A car moving east at 45 km/h turns and travels west at 30 km/h. What is the magnitude and direction of the change in velocity?

Answer 1

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Answer 2

If you've used vectors, let's assign the 45km/h east as positive, and 30km/h west as negative. Then you need to subtract the 45km/h from -30km/h:
-30 - 45 = -75km/h

So our magnitude of change is is 75km/h, and our direction is west (since negative is west).