Difference between Forced Vibrations and Resonant Vibrations

Forced Vibrations:

1. The vibrations of a body under an external periodic force of frequency different from the natural frequency of the body, are called forced vibrations.

2. The amplitude of vibration is small.

3. The vibrations of the body are not in phase with the external periodic force.

4. These vibrations last for a very short time after the periodic force has ceased to act.

Resonant Vibrations:

1. The vibrations of a body under an external periodic force of frequency exactly equal to the natural frequency of the body, are called resonant vibrations.

2. The amplitude of vibration is very large.

3. The vibrations of the body are in phase with the external periodic force.

4. These vibrations last for a long time after the periodic force has ceased to act.