A cyclist rides 3 km west and then turns around and rides 2 km east. What is the magnitude of her displacement?

1. Take west as negative and east as positive (or vice versa) along a single axis. 2. Displacement is the vector sum: -3 km (west) + 2 km (east) = -1 km, i.e. 1 km west of the start. 3. The worked example confirms: "The magnitude of the displacement is 1 km." 4. 5 km is a trap -- that is the total distance ridden (3 km + 2 km), not the net displacement. 5. So the magnitude of displacement is 1 km, not the 5 km total distance covered. _Source: OpenStax Physics Ch 2 "Motion in One Dimension", p.62 Worked Example §2.1 Relative Motion, Distance, and Displacement_