A cyclist rides 3 km west, turns around, and rides 2 km east. Taking east as positive, what are her displacement and the distance she rides?
ADisplacement +1 km and distance 1 km
BDisplacement -5 km and distance 5 km
CDisplacement -1 km and distance 5 km
DDisplacement -1 km and distance 1 km
Answer & Solution
Correct answer: C. Displacement -1 km and distance 5 km
1. Take east as positive, so the westward leg is -3 km and the eastward leg is +2 km.
2. Displacement is the net change in position: -3 km + 2 km = -1 km.
3. Distance travelled is the total path length: 3 km + 2 km = 5 km.
4. The magnitude of the displacement is 1 km, which is not the same as the 5 km ridden.
5. Quoting -5 km confuses the total path length with the net change in position.
_Source: OpenStax College Physics (CC BY 4.0), Ch 2 "Kinematics", section 2.1 Displacement_
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