Define displacement. What is its S.I. unit?

Explanation

### Step-by-Step Solution:

1. **Definition of Displacement**:
- Displacement is defined as the shortest distance between the initial and final positions of an object, along with the direction from the initial position to the final position. It is a vector quantity, which means it has both magnitude and direction.

2. **Magnitude of Displacement**:
- The magnitude of displacement is the straight-line distance between the starting point (initial position) and the ending point (final position) of the object. For example, if an object moves from point A to point B, the magnitude of displacement is the distance measured directly from A to B.

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