Motion — Science STD 9 — Question

Displacement is the shortest distance between two points, while distance is the length of the path travelled. Therefore if the body takes the shortest path between two points, distance and displacement will be equal.
Imagine it in this way: Between two points you can draw any line-curved, with turns, etc, but you can draw only one straight line connecting the points which will be of the shortest distance. If an object travels across the curved line, the distance is equal to the length of the curved line, while displacement is equal to the length of the straight line. In case the object travels asking this straight line, distance will be equal to the length of this line, which is also equal to displacement.