Question

What do you understand about free vibrations of a body?

Answer 1

Vibration is a mechanical phenomenon in which oscillations occur about an equilibrium point. It is a periodic back and forth motion of the particles of an elastic body or medium. The oscillations may be periodic, such as the motion of a pendulum – or random, such as the movement of a tire on a gravel road.

Complete step-by-step solution:
The vibrations of a body in the absence of any external force on it are called the ‘free vibration’. Free vibrations occur when the system is disturbed for a moment and then allowed to move without any restraint or disturbance.
A classic example of free vibration is provided by a weight suspended from a spring. In equilibrium, the system has minimum energy and the weight is at rest. If the weight is pulled down and released, the system will respond by vibrating vertically.
A universal feature of free vibration is ‘damping’. All systems are subjected to frictional forces, and these steadily decrease the energy of the vibrations, causing the amplitude to diminish, usually exponentially. The motion is therefore never precisely sinusoidal. Thus, a swinging pendulum when left undisturbed will eventually return to rest at the equilibrium (minimum-energy) position.
The characteristics of free vibrations are:
1. Constant amplitude
2. Constant frequency
3. Constant energy

Note:- Generally, there are three types of vibration:
->Free Vibration: explained above
->Forced Vibration: It occurs if a system is continuously driven by an external agency.
->Damped Vibration: When the energy of a vibrating system is gradually dissipated by friction and other resistances, the vibrations are said to be damped.