Define resonant vibrations.

Explanation

**Step-by-Step Solution:**

1. **Understanding Vibrations**:
- Begin by defining what vibrations are. Vibrations are oscillations or repetitive motions of an object around an equilibrium position.

2. **Natural Frequency**:
- Explain the concept of natural frequency. Every vibrating body has a natural frequency, which is the frequency at which it tends to vibrate when disturbed.

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