Physics

Physics

Problem

A student walks 20 m east and then 20 m west along the same straight corridor and stops. Which pair correctly represents the distance travelled and the displacement from the starting point? a) Distance=0 m,  Displacement=40 m eastDistance = 0\,\text{m},\; Displacement = 40\,\text{m east} b) Distance=40 m,  Displacement=20 m eastDistance = 40\,\text{m},\; Displacement = 20\,\text{m east} c) Distance=40 m,  Displacement=0 mDistance = 40\,\text{m},\; Displacement = 0\,\text{m} d) Distance=20 m,  Displacement=20 m westDistance = 20\,\text{m},\; Displacement = 20\,\text{m west}
Intuitive explanation

The key is distinguishing between distance (total ground covered, always positive) and displacement (straight-line change in position from start to finish). Here, the student walks 20 m one direction, then 20 m back along the same path—so they retrace their steps. Distance adds up all the walking; displacement measures only where they end up relative to where they started.

Intuitive explanation

The key is distinguishing between distance (total ground covered, always positive) and displacement (straight-line change in position from start to finish). Here, the student walks 20 m one direction, then 20 m back along the same path—so they retrace their steps. Distance adds up all the walking; displacement measures only where they end up relative to where they started.

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