Why does friction occur? Justify your answer.

Explanation

### Step-by-Step Solution:

1. **Understanding Surface Irregularities**:
- Every surface, regardless of how smooth it appears, has tiny irregularities when viewed under a microscope. These irregularities can be thought of as small peaks (mountains) and dips (valleys).

2. **Contact Between Surfaces**:
- When two surfaces come into contact, these irregularities interact with each other. The peaks of one surface can fit into the valleys of the other surface.

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