Types of oscillations and their definitions. Vibrations: mechanical and electromagnetic
1. Fluctuations.
2. Mechanical vibrations.
3. Energy transformations during mechanical vibrations.
4. The period of oscillations.
5. Oscillation frequency.
6. Cyclic oscillation frequency.
7. Amplitude of mechanical oscillations.
8. Harmonic vibrations.
9. Phase of the harmonic oscillation.
10. Analytical representation of oscillations.
11. Graphical representation of vibrations.
12. The speed of a point in a harmonic oscillation.
13. Acceleration of a point in a harmonic oscillation.
14. Dynamics of harmonic oscillation.
15. Oscillation period of a spring pendulum.
16. Mathematical pendulum. quasi-elastic force.
17. Oscillations of a body floating on the surface of a liquid.
18. Oscillations of a homogeneous liquid in a U-shaped tube.
19. Oscillations of a body in a spherical bowl.
20. Energy of harmonic oscillation.
21. Damped vibrations.
22. Forced vibrations.
23. Resonance.
24. Free vibrations. Own frequency.
25. Self-oscillations.
1. Fluctuations. Oscillations are generally called periodic changes in the state of the system, in which the values of various physical quantities characterize this system. For example, periodic changes in air pressure and density, voltage and electric current are fluctuations in these quantities.
Mathematically, periodicity means that if - is a periodic function of time with a period T, then for any t equality 
2. Mechanical vibrations- body movements that are exactly or almost exactly repeated at regular intervals.
Mechanical vibrations occur in systems that have a position of stable equilibrium. According to the principle of minimum potential energy, in the position of stable equilibrium, the potential energy of the system is minimal. When a body is removed from a position of stable equilibrium, its potential energy increases. In this case, a force arises directed to the equilibrium position (returning force), and the farther the body deviates from the equilibrium position, the greater its potential energy and the greater the module of the restoring force. For example, when a spring pendulum deviates from the equilibrium position, the role of the restoring force is played by the elastic force, the modulus of which changes in proportion to the deviation , where X deviation of the pendulum from the equilibrium position. The potential energy of a spring pendulum changes in proportion to the square of the displacement.
Similarly, there are oscillations of a filament pendulum and a ball moving along the bottom of a spherical bowl of radius R, which can be considered as a thread pendulum with a thread length equal to the bowl radius (Fig. 78).
3.Energy transformations during mechanical vibrations. If there are no friction forces, then the total mechanical energy of an oscillating body remains constant. In the process of oscillations, periodic mutual transformations of the potential and kinetic energy of the body occur. Let us carry out the reasoning on the example of the oscillations of a thread pendulum. To simplify the reasoning, we take the potential energy of the pendulum in the equilibrium position equal to zero. In the extreme deflected position, the potential energy of the pendulum is maximum, and the kinetic energy is zero, because. in this position the pendulum is at rest. When moving to the equilibrium position, the height of the pendulum above the Earth's surface decreases, and the potential energy decreases, while its speed and kinetic energy increase. In the equilibrium position, the potential energy is zero, and the kinetic energy is maximum. Continuing to move by inertia, the pendulum passes the equilibrium position. After passing the equilibrium position, the kinetic energy of the pendulum decreases, but its potential energy increases. When the pendulum stops, its kinetic energy will become equal to zero, and the potential energy will reach a maximum and everything will be repeated in the reverse order.
According to the law of conservation of energy, the potential energy of the pendulum in the extreme deflected position is equal to its kinetic energy at the moment of passing through the equilibrium position.
In the process of oscillation at any moment of time, the total mechanical energy of the pendulum is equal to its potential in the extreme deflected position or the kinetic energy at the moment of passing the equilibrium position
where the height of the pendulum in the extreme deflected position, the speed at the moment of passing through the equilibrium position.
4. Oscillation period- the minimum time interval after which the movement is repeated, or the time interval during which one complete oscillation occurs. Period ( T) is measured in seconds.
5. Oscillation frequency- determines the number of complete oscillations made in one second. Frequency and period are related by
Frequency is measured in hertz (Hz). One hertz is one complete oscillation in one second.
6. Cyclic frequency or circular frequency determines the number of complete oscillations per second
Frequency is a positive value , .
7. Amplitude of mechanical vibrations is the maximum deviation of the body from the equilibrium position. In the general case of oscillations, the amplitude is the maximum value that a periodically changing physical quantity takes.
8. Harmonic vibrations- oscillations in which the oscillating value changes according to the law of sine or cosine (according to the harmonic law):
Here is the oscillation amplitude, cyclic frequency.
9. Phase of the harmonic oscillation - magnitude , standing under the sign of sine or cosine. The phase determines the value of the fluctuating quantity at a given time, the initial phase, i.e. at the moment of the beginning of the time reference The simplest example of harmonic oscillations is the oscillation of the projection on the coordinate axes of the point m moving uniformly along a circle of radius BUT in plane XOY, whose center coincides with the origin (Fig. 79)
For simplicity, we set , i.e. then
Many well-known oscillatory systems can only approximately be considered harmonic only approximately for very small deviations. The main condition for harmonic oscillation is the constancy of the cyclic frequency and amplitude. For example, when a thread pendulum oscillates, the angle of deviation from the vertical changes unevenly, i.e. the cyclic frequency is not constant. If the deviations are very small, then the movement of the pendulum is very slow and the unevenness of the movement can be neglected, assuming . The slower the movement, the lower the resistance of the medium, the lower the energy loss and the smaller the change in amplitude.
Thus, small oscillations can be approximately considered harmonic.
10. Analytical representation of vibrations- record of the fluctuating value in the form of a function expressing the dependence of the value on time.
11. Graphical representation of vibrations - representation of oscillations in the form of a graph of a function in the coordinate axes OX and t.
For example, analytically harmonic oscillations are written as , and its graphical representation is depicted as a sinusoid - a solid line in Fig.80.
12.Point velocity in harmonic oscillation– we obtain, by differentiating with respect to time, the function X(t)
Where is the velocity amplitude, proportional to the cyclic frequency and displacement amplitude.
So the speed V according to a sinusoidal law with the same period T, which is the offset X within 
. The velocity phase leads the displacement phase by . This means that the speed is maximum when the point passes the equilibrium position, and at maximum displacements of the point, its speed is zero. The speed graph is represented by a dotted line in Fig. 80
13. Acceleration of a point during harmonic oscillations obtained by differentiating the speed with respect to time or differentiating the displacement X twice in time:
Where is the acceleration amplitude proportional to the displacement amplitude and the square of the cyclic frequency.
Acceleration of a point during harmonic oscillations changes according to a sinusoidal law with the same period T, which is the shift within 
The acceleration phase leads the displacement phase by . The acceleration is equal to zero at the moment the point passes the equilibrium position. In Fig. 81, the acceleration graph is shown by a dotted line, the solid line depicts the displacement graph.
Considering that we write the acceleration in the form
Those. acceleration in a harmonic oscillation is proportional to the displacement and is always directed towards the equilibrium position (against the displacement). Moving away from the equilibrium position, the point moves rapidly, approaching the equilibrium position, the point moves rapidly.
14. Dynamics of harmonic oscillation. Multiplying the acceleration of a point that makes a harmonic oscillation, by its mass, we obtain, according to Newton's second law, the force acting on the point
Denote Now we write the force acting on the point
It follows from the last equality that harmonic oscillations are caused by a force proportional to the displacement and directed against the displacement, i.e. to the equilibrium position.
15. Period of oscillation of a spring pendulum. A spring pendulum oscillates under the action of an elastic force
A force proportional to the displacement and directed towards the equilibrium position causes harmonic oscillations of the point. Therefore, the oscillations of a spring pendulum are harmonic. The stiffness coefficient is
Keeping in mind that we get the period of free oscillations of the spring pendulum
The frequency of the spring pendulum is
.
15. Mathematical pendulum- a material point suspended on an infinitely thin, weightless, inextensible thread, oscillating in a vertical plane, under the action of gravity.
A load suspended on a thread, the dimensions of which are negligible compared to the length of the thread, can be approximately considered a mathematical pendulum. Often such a pendulum is called a thread pendulum.
Consider small oscillations of a mathematical pendulum with length l. In the equilibrium position, the force of gravity is balanced by the tension in the thread, i.e. .
If we deviate the pendulum through a small angle, then the force of gravity and the force of tension, directed at an angle to each other, add up to the resultant force, which is directed towards the equilibrium position. In Fig. 82, the deviation of the pendulum from the vertical is
The angle is so small that the cyclic frequency, i.e. the angular velocity of rotation of the thread can be considered constant. Therefore, we write the displacement of the pendulum in the form
Thus, small oscillations of a mathematical pendulum are harmonic oscillations. From Fig. 82 it follows that the force is but therefore
Where m, g, and l constant values. Let us denote and obtain the module of the restoring force in the form . If we take into account that the force is always directed towards the equilibrium position, i.e. against the bias, then we write its expression in the form .
So, the force causing oscillations of a mathematical pendulum is proportional to the displacement and directed against the displacement, as in the case of oscillations of a spring pendulum, i.e. the nature of this force is the same as the elastic force. But by nature, the elastic force is an electromagnetic force. The force that causes oscillations of a mathematical pendulum is by its nature a gravitational force - non-electromagnetic, therefore it is called quasi-elastic by force. Any force that acts as an elastic force that is not electromagnetic in nature is called a quasi-elastic force. This allows us to write the expression for the period of oscillation of a mathematical pendulum in the form
.
It follows from this equality that the period of oscillation of a mathematical pendulum does not depend on the mass of the pendulum, but depends on its length and free fall acceleration. Knowing the period of oscillation of a mathematical pendulum and its length, it is possible to determine the acceleration of free fall at any point on the surface of the Earth.
17. Vibrations of a body floating on the surface of a liquid. For simplicity, consider a body of mass m in the form of a cylinder with a base area S. The body floats partially immersed in a liquid whose density is (Fig. 83).
Let the immersion depth be in the equilibrium position. In this case, the resultant force of Archimedes and the force of gravity is equal to zero
.
If you change the immersion depth to X then the force of Archimedes will become equal and the modulus of the resultant force F becomes different from zero
Given that 
we get
Denoting , the modulus of force F as
If the immersion depth increases, i.e. the body moves down, the Archimedes force becomes greater than the force of gravity and the resultant F directed upwards, i.e. against displacement. If the immersion depth decreases, i.e. shifts upward from the equilibrium position, the Archimedes force becomes less than the force of gravity and the resultant F directed downward, i.e. against displacement.
So the strength F always directed against the displacement and its modulus is proportional to the displacement
This force is quasi-elastic and it causes harmonic oscillations of a body floating on the surface of a liquid. The period of these oscillations is calculated by the formula common for harmonic oscillations
.
18. Oscillations of a homogeneous liquid in a U-tube. Let a homogeneous fluid of mass m, the density of which is poured into a U - shaped tube, the cross-sectional area of \u200b\u200bwhich S(Fig.84) In a state of equilibrium, the heights of the columns in both elbows of the tube are the same, according to the law of communicating vessels for a homogeneous liquid.
If the liquid is taken out of equilibrium, then the heights of the liquid columns in the knees will change periodically, i.e. the liquid in the tube will oscillate.
Let at some point in time the height of the liquid column in the right knee be X more. than on the left. This means that the liquid in the tube is affected by the gravity of the liquid in a column with a height X, , where is the volume of the liquid column with height x. The product is a constant, so .
So the modulus of force F is proportional to the difference in the heights of the liquid columns in the elbows, i.e. proportional to the displacement of the liquid in the tube. The direction of this force is always opposite to the displacement, i.e.
Therefore, this force causes harmonic oscillations of the liquid in the tube. We write the period of these oscillations according to the rule for harmonic oscillations
19. Oscillations of a body in a spherical bowl. Let the body slide without friction in a spherical bowl of radius R(Fig. 78). With small deviations from the equilibrium position, the oscillations of this body can be considered as harmonic oscillations of a mathematical pendulum, the length of which is equal to R, with a period equal to
20. Energy of harmonic oscillation. As an example, consider the oscillation of a spring pendulum. When offset X
If the friction force is very high, then damped oscillations do not occur. The body, brought out of equilibrium by any forces, after the termination of the action of these forces, returns to the equilibrium position and stops. Such motion is called aperiodic (non-periodic). The aperiodic motion graph is shown in Fig.86.
22. Forced vibrations- undamped oscillations of the system, which are caused by external forces periodically changing over time (forcing forces).
If the driving force changes according to the harmonic law
, where the amplitude of the driving force is its cyclic frequency, then forced harmonic oscillations with a cyclic frequency equal to the frequency of the driving force can be established in the system
.
23. Resonance- a sharp increase in the amplitude of forced oscillations when the frequency of the driving force coincides with the frequency of free oscillations of the system . If the oscillation occurs in a resisting medium, then the plot of the dependence of the amplitude of the forced oscillations on the frequency of the driving force looks like in Fig. 87
The driving force, the frequency of which coincides with the frequency of free oscillations of the system, even with very small amplitudes of the driving force, can cause oscillations with a very large amplitude.
24. Free vibrations. Natural frequency of the system. Free vibrations are the vibrations of a system that occur under the action of its internal forces. For a spring pendulum, the internal force is the elastic force. For a mathematical pendulum, which consists of the pendulum itself and the Earth, the internal force is gravity. For a body floating on the surface of a liquid, the internal force is the Archimedes force.
25. Self-oscillations- undamped oscillations occurring in the medium, due to an energy source that does not have oscillatory properties, compensating for energy losses to overcome friction forces. Self-oscillating systems receive equal portions of energy at equal time intervals, for example, after one period. Clocks are an example of a self-oscillating system.
Belarusian National Technical University
Department of "Technical Physics"
Laboratory of Mechanics and Molecular Physics
Report
for laboratory work SP 1
“Vibrations and Waves.
Completed by: student gr.107624
Khikhol I.P.
Checked by: Fedotenko A.V.
Minsk 2004
Questions:
What movement is called oscillatory? Types of fluctuations? What vibrations are called harmonic? Basic characteristics of harmonic oscillation.
What vibrations are called free? Give examples of free vibrations.
What vibrations are called forced? Give examples of forced oscillations.
Describe the process of energy conversion during harmonically oscillatory motion, using the example of a mathematical or spring pendulum.
By what formula is the total mechanical energy determined during the harmonic oscillation of the body at the moment of passing the equilibrium point and the extreme points of movement.
Why do free oscillations of a pendulum damp out? Under what conditions can the oscillations of a pendulum become undamped?
What is mechanical resonance? What is the resonance condition? Types of resonance. Examples of resonant systems. Give an example of a useful and harmful manifestation of resonance.
What is a self oscillatory system? Give an example of a device for obtaining self-oscillations. What is the difference between self-oscillations and forced and free oscillations?
What is called a wave? The main characteristics of the wave process. Wave types.
What waves are called transverse, longitudinal? What is the difference between them? Give examples of transverse and longitudinal waves?
Which wave is called linear, spherical, plane? What properties do they have?
How are waves reflected from an obstacle? What is a standing wave? Its main characteristics. Give examples.
Application of wave processes. How is a radio telescope antenna arranged?
Sound waves and their applications.
Answers:
1 Oscillations are processes that differ in one degree or another of repetition.
There are vibrations: mechanical, electromagnetic, electromechanical.
Harmonic oscillations are those oscillations in which the oscillating value changes according to the sin or cos law.
The main characteristics of a harmonic oscillation: amplitude, wavelength, frequency.
2 Free oscillations are called: oscillations that occur in a system left to itself after a push has been given to it or it has been taken out of equilibrium
An example of free vibrations: vibrations of a ball suspended on a thread.
3 Forced oscillations are called: oscillations, during which the oscillating system is exposed to an external periodically changing force.
An example of forced vibrations: the vibrations of a bridge that occur when people walk along it, walking in step.
4 In a harmonically oscillatory motion, energy passes from kinetic to potential energy and vice versa. The sum of the energies is equal to the maximum energy.
5 According to the formula, the total mechanical energy is determined during the harmonic oscillation of the body at the moment of passing the equilibrium point, 
extreme points of movement.
6 Free oscillations of the pendulum damp out as the body is affected by a force that prevents its movement (forces of friction, resistance).
Pendulum oscillations can become undamped if energy is constantly supplied.
7 Resonance - the maximum increase in amplitude.
Resonance condition: when the natural frequency of the system must match the translational.
Examples of resonant systems:
An example of a useful manifestation of resonance: used in acoustics, radio engineering (radio receiver). An example of a harmful manifestation of resonance: the destruction of bridges when marching columns pass over them.
8 Self-oscillatory system - these are oscillations accompanied by the influence of external forces on the oscillatory system, however, the moments of time when these effects are carried out are set by the oscillatory system itself - the system itself controls external forces.
An example of a device for obtaining self-oscillations: a clock in which the pendulum receives shocks due to the energy of a raised weight or a twisted spring, and these shocks occur at the moment the pendulum passes through the middle position.
The difference between self-oscillations and forced and free oscillations is that energy is supplied to this system from outside, but this energy supply is controlled by the system itself.
9 A wave is an oscillation that propagates through space over time.
Characteristics of the wave process: wavelength, wave propagation speed, wave amplitude
Waves are transverse and longitudinal.
10 Transverse waves - particles of the medium oscillate, remaining in planes perpendicular to the propagation of the wave.
Longitudinal waves - particles of the medium oscillate in the direction of wave propagation
An example of transverse waves is sound waves, longitudinal waves are radio waves.
11 A linear wave is a wave that propagates in parallel lines.
A spherical wave propagates in all directions from the point that causes it to oscillate, and the crests resemble spheres.
A wave is considered flat if its wave surfaces are a set of planes parallel to each other.
12 The wave is reflected at the same angle to the normal as the incident wave at that point.
A standing wave is formed in a homogeneous medium when two identical waves propagate towards each other through this medium: traveling and oncoming. As a result of superposition (superposition of these forms), a standing wave arises.
Characteristics: amplitude, frequency.
Example: two wave sources are in the water, they create the same wave, there will be standing waves between these sources.
13 Wave processes are used in the transmission of signals over a distance.
Waves incident on the plane of the antenna are reflected in parallel and intersect at one point where resonance occurs
14 Sound waves propagate as longitudinal mechanical waves. The speed of propagation of these waves depends on the mechanical properties of the medium and does not depend on the frequency.
Literature:
Sivukhin D.V. General course physics, v., ch.2, §17. M., "Science", 1989.
Detlaf A., A. Yavorsky B. M. "Higher School", 1998.
Gevorkyan R.G. Shepel
Trofimoza T.I. Physics course, M. "Higher School", 1998.
Sazeleva I.V. Course of general physics, vol. 1, ch. 2, §15. M., "Nauka", 1977.
Narakevich I.I., Volmyansky E.I., Lobko S.I. Physics for VTUs. - Minsk. Graduate School. 1992
), oscillations that occur due to the energy imparted to the system at the beginning of the oscillatory motion (for example, in a mechanical system through the initial displacement of the body or giving it an initial speed, and in an electrical system - an oscillatory circuit - through the creation of an initial charge on the capacitor plates). The amplitude of natural oscillations, in contrast to forced oscillations, is determined only by this energy, and their frequency is determined by the properties of the system itself. Due to energy dissipation, natural oscillations are always damped oscillations. An example of natural vibrations is the sound of a bell, gong, piano string, etc.
Modern Encyclopedia. 2000 .
See what "OWN OSCILLATIONS" is in other dictionaries:
Natural vibrations- (free vibrations), vibrations that occur due to the energy imparted to the system at the beginning of the oscillatory movement (for example, in a mechanical system through the initial displacement of the body or giving it an initial speed, and in an electrical ... ... Illustrated Encyclopedic Dictionary
Vibrations in any vibration. system occurring in the absence of external influence; the same as (see FREE VIBRATIONS). Physical Encyclopedic Dictionary. Moscow: Soviet Encyclopedia. Editor-in-Chief A. M. Prokhorov. 1983... Physical Encyclopedia
- (free oscillations) oscillations that can be excited in an oscillatory system under the influence of an initial push. The shape and frequency of natural vibrations are determined by the mass and elasticity for mechanical natural vibrations and inductance and ... ... Big Encyclopedic Dictionary
- (Oscillations) free vibrations of a body or an oscillating circuit by inertia, when they are not affected by a periodic external force. S. K. have a very definite period (own period); e.g. the ship's vibrations after it ... ... Marine Dictionary
natural vibrations- Free oscillations on one of own forms. [Collection of recommended terms. Issue 82. Structural mechanics. USSR Academy of Sciences. Committee of Scientific and Technical Terminology. 1970] Topics structural mechanics, strength of materials EN ... Technical Translator's Handbook
- (free vibrations), vibrations that can be excited in an oscillatory system under the action of an initial push. The shape and frequency of mechanical natural oscillations are determined by mass and elasticity, and electromagnetic inductance and ... ... encyclopedic Dictionary
natural vibrations- savieji virpesiai statusas T sritis fizika atitikmenys: angl. eigen oscillations; natural oscillations; self oscillations vok. Eigenschwingungen, f rus. natural oscillations, n pranc. oscillations propres, f … Fizikos terminų žodynas
Free vibrations, vibrations that occur in a dynamic system in the absence of an external influence when an external perturbation is communicated to it at the initial moment, which brings the system out of equilibrium. The character of S. to. is mainly determined by ... ... Mathematical Encyclopedia
natural vibrations- ▲ physical oscillations independent natural [free] oscillations occur under the influence of the initial push. self-oscillations. self-excitation is the spontaneous occurrence of oscillations in the system under the influence of external influences. spectrum. triplet ... Ideographic Dictionary of the Russian Language
Free oscillations, oscillations in a mechanical, electrical or any other physical system, occurring in the absence of external influence due to the initially accumulated energy (due to the presence of an initial displacement or ... Great Soviet Encyclopedia
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fluctuations- movements that are exactly or approximately repeated at certain intervals of time.
Free vibrations- fluctuations in the system under the action of internal bodies, after the system is taken out of equilibrium.
The vibrations of a weight suspended from a string or a weight attached to a spring are examples of free vibrations. After removing these systems from the equilibrium position, conditions are created under which the bodies oscillate without the influence of external forces.
System- a group of bodies, the movement of which we study.
internal forces- forces acting between the bodies of the system.
Outside forces- forces acting on the bodies of the system from the bodies that are not included in it.
Conditions for the occurrence of free oscillations.
- When the body is removed from the equilibrium position, a force must arise in the system directed towards the equilibrium position and, therefore, tending to return the body to the equilibrium position.
Example: when the ball attached to the spring moves to the left and when it moves to the right, the elastic force is directed towards the equilibrium position. - The friction in the system must be sufficiently low. Otherwise, the oscillations will quickly die out or not appear at all. Continuous oscillations are possible only in the absence of friction.
Exist different types oscillations in physics, characterized by certain parameters. Consider their main differences, classification according to various factors.
Basic definitions
Oscillation is understood as a process in which, at regular intervals, the main characteristics of the movement have the same values.
Such oscillations are called periodic, in which the values of the basic quantities are repeated at regular intervals (period of oscillations).
Varieties of oscillatory processes
Let us consider the main types of oscillations that exist in fundamental physics.
Free vibrations are those that occur in a system that is not subjected to external variable influences after the initial shock.
An example of free oscillations is a mathematical pendulum.
Those types of mechanical vibrations that occur in the system under the action of an external variable force.
Features of the classification
According to the physical nature, the following types of oscillatory movements are distinguished:
- mechanical;
- thermal;
- electromagnetic;
- mixed.
According to the option of interaction with the environment
Types of vibrations by interaction with environment distinguish several groups.
Forced oscillations appear in the system under the action of an external periodic action. As examples of this type of oscillation, we can consider the movement of hands, leaves on trees.
For forced harmonic oscillations, a resonance may appear, in which, with equal values of the frequency of the external action and the oscillator, with a sharp increase in amplitude.
Natural vibrations in the system under the influence of internal forces after it is taken out of equilibrium. The simplest variant of free vibrations is the movement of a load that is suspended on a thread or attached to a spring.
Self-oscillations are called types in which the system has a certain amount of potential energy used to make oscillations. hallmark their is the fact that the amplitude is characterized by the properties of the system itself, and not by the initial conditions.
For random oscillations, the external load has a random value.
Basic parameters of oscillatory movements
All types of oscillations have certain characteristics, which should be mentioned separately.
Amplitude is the maximum deviation from the equilibrium position, the deviation of a fluctuating value, it is measured in meters.
The period is the time of one complete oscillation, after which the characteristics of the system are repeated, calculated in seconds.
The frequency is determined by the number of oscillations per unit of time, it is inversely proportional to the period of oscillation.
The oscillation phase characterizes the state of the system.
Characteristic of harmonic vibrations
Such types of oscillations occur according to the law of cosine or sine. Fourier managed to establish that any periodic oscillation can be represented as a sum of harmonic changes by expanding a certain function in
As an example, consider a pendulum having a certain period and cyclic frequency.
What characterizes these types of oscillations? Physics considers an idealized system, which consists of material point, which is suspended on a weightless inextensible thread, oscillates under the influence of gravity.
Such types of vibrations have a certain amount of energy, they are common in nature and technology.
With prolonged oscillatory motion, the coordinates of its center of mass change, and with alternating current, the value of current and voltage in the circuit changes.
There are different types of harmonic oscillations according to their physical nature: electromagnetic, mechanical, etc.
Shaking acts as a forced vibration vehicle, which moves on a rough road.
The main differences between forced and free vibrations
These types of electromagnetic oscillations differ in physical characteristics. The presence of medium resistance and friction forces lead to damping of free oscillations. In the case of forced oscillations, energy losses are compensated by its additional supply from an external source.
The period of a spring pendulum relates the mass of the body and the stiffness of the spring. In the case of a mathematical pendulum, it depends on the length of the thread.
With a known period, it is possible to calculate the natural frequency of the oscillatory system.
In technology and nature, there are fluctuations with different values frequencies. For example, the pendulum that oscillates in St. Isaac's Cathedral in St. Petersburg has a frequency of 0.05 Hz, while for atoms it is several million megahertz.
After a certain period of time, the damping of free oscillations is observed. That is why forced oscillations are used in real practice. They are in demand in a variety of vibration machines. The vibratory hammer is a shock-vibration machine, which is intended for driving pipes, piles, and other metal structures into the ground.
Electromagnetic vibrations
Characteristics of vibration modes involves the analysis of the main physical parameters: charge, voltage, current strength. As an elementary system, which is used to observe electromagnetic oscillations, is an oscillatory circuit. It is formed by connecting a coil and a capacitor in series.
When the circuit is closed, free electromagnetic oscillations arise in it, associated with periodic changes in the electric charge on the capacitor and the current in the coil.
They are free due to the fact that when they are performed there is no external influence, but only the energy that is stored in the circuit itself is used.
In the absence of external influence, after a certain period of time, attenuation of the electromagnetic oscillation is observed. The reason for this phenomenon will be the gradual discharge of the capacitor, as well as the resistance that the coil actually has.
That is why damped oscillations occur in a real circuit. Reducing the charge on the capacitor leads to a decrease in the energy value in comparison with its original value. Gradually, it will be released in the form of heat on the connecting wires and the coil, the capacitor will be completely discharged, and the electromagnetic oscillation will be completed.
The Significance of Fluctuations in Science and Technology
Any movements that have a certain degree of repetition are oscillations. For example, a mathematical pendulum is characterized by a systematic deviation in both directions from the original vertical position.
For a spring pendulum, one complete oscillation corresponds to its movement up and down from the initial position.
In an electrical circuit that has capacitance and inductance, there is a repetition of charge on the plates of the capacitor. What is the cause of oscillatory movements? The pendulum functions due to the fact that gravity causes it to return to its original position. In the case of a spring model, a similar function is performed by the elastic force of the spring. Passing the equilibrium position, the load has a certain speed, therefore, by inertia, it moves past the average state.
Electrical oscillations can be explained by the potential difference that exists between the plates of a charged capacitor. Even when it is completely discharged, the current does not disappear, it is recharged.
In modern technology, oscillations are used, which differ significantly in their nature, degree of repetition, character, and also the "mechanism" of occurrence.
Mechanical vibrations are made by the strings of musical instruments, sea waves, and a pendulum. Chemical fluctuations associated with a change in the concentration of reactants are taken into account when conducting various interactions.
Electromagnetic oscillations make it possible to create various technical devices, for example, a telephone, ultrasonic medical devices.
Cepheid brightness fluctuations are of particular interest in astrophysics, and scientists from different countries are studying them.
Conclusion
All types of oscillations are closely related to a huge number of technical processes and physical phenomena. Their practical importance is great in aircraft construction, shipbuilding, the construction of residential complexes, electrical engineering, radio electronics, medicine, and fundamental science. An example of a typical oscillatory process in physiology is the movement of the heart muscle. Mechanical vibrations are found in organic and inorganic chemistry, meteorology, and also in many other natural sciences.
The first studies of the mathematical pendulum were carried out in the seventeenth century, and by the end of the nineteenth century, scientists were able to establish the nature of electromagnetic oscillations. The Russian scientist Alexander Popov, who is considered the "father" of radio communications, conducted his experiments precisely on the basis of the theory of electromagnetic oscillations, the results of research by Thomson, Huygens, and Rayleigh. He managed to find a practical application for electromagnetic oscillations, to use them to transmit a radio signal over a long distance.
Academician P. N. Lebedev for many years conducted experiments related to the production of high-frequency electromagnetic oscillations using alternating electric fields. Through numerous experiments related to various types fluctuations, scientists managed to find areas of their optimal use in modern science and technology.