the physical world around us is full of movement.It is almost impossible to find at least one physical body, which could be regarded as being at rest.Also uniformly straight forward motion, the motion of a complex trajectory, movement acceleration and others, we can observe or experience first hand the impact of recurrent movements of material objects.
man had noticed the distinctive characteristics and features of the vibrational motions, and even learned to use mechanical vibrations for their own purposes.All recurring time processes can be called oscillations.Mechanical vibrations are only part of the diverse world of the phenomena occurring in practically the same laws.In the illustrative example of mechanical repetitive movements can make the basic rules and to determine the laws that occur electromagnetic, electromechanical and other oscillatory processes.
The nature of mechanical vibrations lies in the periodic conversion of potential energy into kinetic energy.Describe an example of how the transformation of energy in the mechanical vibrations can be considering a ball suspended on a spring.In repose the force of gravity is balanced by the elastic force of the spring.But it is necessary to bring the system out of balance force, thus triggering a movement toward the equilibrium point, the potential energy will begin its transformation into kinetic energy.And that, in turn, since the ball passing position zero begins to be transformed into potential energy.This process occurs so long as the conditions of existence of the system close to perfect.
Mathematically considered ideal vibrations occurring on the sine or cosine law.Such processes are called harmonic oscillations.A perfect example is a mechanical harmonic oscillations of a pendulum motion in absolutely empty space where there is no influence of friction forces.But it is absolutely perfect case to achieve which is technically very problematic.
mechanical vibrations, regardless of their duration, sooner or later stop, and the system occupies a position of relative equilibrium.This happens because of the waste of energy to overcome air resistance, friction and other factors, will inevitably lead to an adjustment of calculations during the transition from the ideal to the real conditions in which there is the system under consideration.
, inevitably approaching a deeper study and analysis, we need to mathematically describe the mechanical vibrations.Formula this process include values such as amplitude (A), the oscillation frequency (w), the initial phase (a).A function of the displacement (x) versus time (t) in the form of classic looks
x = Acos (wt + a).
also worth mentioning the value characterizing the mechanical vibrations, having a name - the period (T), which is defined mathematically as
T = 2π / w.
mechanical vibrations, in addition to describing the visibility of non-mechanical oscillation processes of nature, we are interested in some of the properties that, when used properly, can have some benefit, but if left unattended - lead to significant trouble.
Particular attention is needed to the phenomenon of a sharp jump in the amplitude of forced oscillations, coming when the frequency of the impact of the driving force to the natural frequency of the body.It is called resonance.Widely used in electronics, in mechanical systems resonance phenomenon basically exhibits destructive nature, it must be considered when creating a wide variety of mechanical structures and systems.
next manifestation of mechanical vibrations is a vibration.Her appearance can have not only a certain discomfort, but also bring to the appearance of resonance.But apart from the negative impact, local vibrations with a small intensity of symptoms may favorably influence overall on the human body, improving the functional state of the central nervous system, and even accelerate the healing of wounds, etc.
Among the options manifestations of mechanical vibrations can distinguish the phenomenon of sound, ultrasound.Useful properties of mechanical waves and other forms of mechanical vibrations are widely used in various sectors of human activity.
