Energy is what makes life not only on our planet, but also in the Universe. However, it can be very different. So, heat, sound, light, electricity, microwaves, calories are various types of energy. For all processes occurring around us, this substance is necessary. All that exists on Earth receives most of the energy from the Sun, but there are other sources as well. The sun transfers it to our planet as much as 100 million of the most powerful power plants would be worked out simultaneously.
What is energy?
The theory put forward by Albert Einstein explores the relationship of matter and energy. This great scientist was able to prove the ability of one substance to turn into another. It turned out that energy is the most important factor in the existence of bodies, and matter is secondary.
Energy is, by and large, the ability to do some work. It is she who stands behind the concept of force that can move the body or give it new properties. What does the term "energy" mean? Physics is a fundamental science that many scientists from different eras and countries have dedicated their lives to. Aristotle also used the word "energy" to denote human activity. Translated from the Greek language, "energy" is "activity", "strength", "action", "power". The first time this word appeared in a treatise by a Greek scientist under the name "Physics".
In the generally accepted sense, this term was coined by the British physicist Thomas Young. This momentous event happened back in 1807. In the 50s of the XIX century. the English mechanic William Thomson first used the concept of kinetic energy, and in 1853 the Scottish physicist William Rankin introduced the term potential energy.
Today, this scalar quantity is present in all branches of physics. It is a single measure of various forms of motion and interaction of matter. In other words, it is a measure of the transformation of some forms into others.
Units and designations
The amount of energy is measured in joules (J). This special unit, depending on the type of energy, can have different designations, for example:
- W is the total energy of the system.
- Q is thermal.
- U is potential.
Types of energy
In nature, there are many different types of energy. The main ones are:
- mechanical;
- electromagnetic;
- electric;
- chemical;
- thermal;
- nuclear (atomic).
There are other types of energy: light, sound, magnetic. In recent years, an increasing number of physicists are inclined to the hypothesis of the existence of so-called "dark" energy. Each of the previously listed types of this substance has its own characteristics. For example, the energy of sound can be transmitted using waves. They contribute to the vibration of the eardrum in the ear of humans and animals, through which you can hear sounds. During various chemical reactions, the energy necessary for the life of all organisms is released. Any fuel, food, batteries, batteries are the storage of this energy.
Our luminary gives the Earth energy in the form of electromagnetic waves. Only in this way can she overcome the vastness of Cosmos. Thanks to modern technologies such as solar panels, we can use it with the greatest effect. Excess unused energy is accumulated in special energy storages. Along with the above types of energy, thermal springs, rivers, tides of the ocean, and biofuels are often used.
Mechanical energy
This type of energy is studied in a section of physics called “Mechanics”. It is indicated by the letter E. Its measurement is carried out in joules (J). What is this energy? Physics of mechanics studies the motion of bodies and their interaction with each other or with external fields. In this case, the energy due to the movement of bodies is called kinetic (denoted by Ek), and the energy due to the interaction of bodies or external fields is called potential (En). The sum of the movement and interaction is the total mechanical energy of the system.
There is a general rule for calculating both types. To determine the amount of energy, the work necessary to transfer the body from the zero state to this state should be calculated. Moreover, the more work, the more energy the body will have in this state.
Separation of species according to different characteristics
There are several types of energy separation. For various reasons, it is divided into: external (kinetic and potential) and internal (mechanical, thermal, electromagnetic, nuclear, gravitational). Electromagnetic energy, in turn, is divided into magnetic and electrical, and nuclear energy into energy of weak and strong interaction.
Kinetic
Any moving bodies are distinguished by the presence of kinetic energy. It is often called driving. The energy of the body that moves is lost when it slows down. Thus, the faster the speed, the greater the kinetic energy.
Upon contact of a moving body with a motionless object, the kinetic part is transferred to the latter, which also causes it to move. The kinetic energy formula is as follows:
- E to = mv 2: 2,
where m is the mass of the body, v is the speed of the body.
In words, this formula can be expressed as follows: the kinetic energy of an object is equal to half the product of its mass and the square of its speed.
Potential
This type of energy is possessed by bodies that are in some kind of force field. So, magnetic occurs when an object is under the influence of a magnetic field. All bodies on earth have potential gravitational energy.
Depending on the properties of the objects of study, they can have different types of potential energy. So, elastic and elastic bodies that are able to stretch have the potential energy of elasticity or tension. Any falling body that was previously motionless loses its potential and acquires kinetic. Moreover, the magnitude of these two species will be equivalent. In the gravitational field of our planet, the potential energy formula will have the following form:
- E n = mhg,
where m is the body weight; h is the height of the center of mass of the body above the zero level; g is the acceleration of gravity.
In words, this formula can be expressed as follows: the potential energy of an object interacting with the Earth is equal to the product of its mass, the acceleration of gravity and the height at which it is located.
This scalar value is a characteristic of the energy reserve of a material point (body) located in a potential force field and used to acquire kinetic energy due to the work of field forces. Sometimes it is called the coordinate function, which is the term in the Langrangian of the system (the Lagrange function of a dynamical system). This system describes their interaction.
Potential energy is equated to zero for a certain configuration of bodies located in space. The choice of configuration is determined by the convenience of further calculations and is called “normalization of potential energy”.
Law of energy conservation
One of the most basic tenets of physics is the law of conservation of energy. According to it, energy does not appear anywhere and does not disappear anywhere. She constantly moves from one form to another. In other words, only a change in energy occurs. So, for example, the chemical energy of the battery of a flashlight is converted into electrical energy, and from it into light and heat. Various household appliances turn electrical into light, heat or sound. Most often, the end result of change is heat and light. After that, the energy goes into the surrounding space.
The law of energy is able to explain many physical phenomena. Scientists claim that its total volume in the Universe constantly remains unchanged. No one can create energy again or destroy it. Developing one of its types, people use the energy of fuel, falling water, an atom. In this case, one of its appearance turns into another.
In 1918, scientists were able to prove that the law of conservation of energy is a mathematical consequence of the translational symmetry of time - the magnitude of the conjugate energy. In other words, energy is conserved due to the fact that the laws of physics do not differ at different points in time.
Energy Features
Energy is the body’s ability to do work. In closed physical systems, it persists throughout the entire time (while the system is closed) and is one of three additive integrals of motion that preserve the value during motion. These include: energy, angular momentum, momentum. The introduction of the concept of "energy" is advisable when the physical system is homogeneous in time.
The internal energy of bodies
It is the sum of the energies of molecular interactions and the thermal motions of the molecules that make it up. It cannot be measured directly, since it is an unambiguous function of the state of the system. Whenever a system is in a given state, its internal energy has its inherent significance, regardless of the history of the system. The change in internal energy in the process of transition from one physical state to another is always equal to the difference between its values in the final and initial states.
Gas internal energy
In addition to solids, gases also have energy. It represents the kinetic energy of the thermal (chaotic) motion of the particles of the system, which include atoms, molecules, electrons, nuclei. The internal energy of an ideal gas (a mathematical model of gas) is the sum of the kinetic energies of its particles. In this case, the number of degrees of freedom, which is the number of independent variables that determine the position of the molecule in space, is taken into account.
Energy use
Every year, humanity consumes an increasing number of energy resources. Most often, fossil fuels such as coal, oil and gas are used to obtain the energy necessary for lighting and heating our homes, operating vehicles and various mechanisms. They relate to non-renewable resources.
Unfortunately, only an insignificant part of the energy is extracted on our planet using renewable resources such as water, wind and the Sun. Today, their share in the energy sector is only 5%. Another 3% of people receive in the form of nuclear energy produced in nuclear power plants.
Non-renewable resources have the following reserves (in joules):
- nuclear energy - 2 x 10 24 ;
- energy of gas and oil - 2 x 10 23 ;
- the internal heat of the planet is 5 x 10 20 .
Annual value of renewable resources of the Earth:
- the energy of the Sun - 2 x 10 24 ;
- wind - 6 x 10 21 ;
- rivers - 6.5 x 10 19 ;
- sea tides - 2.5 x 10 23 .
Only with a timely transition from the use of non-renewable energy reserves of the Earth to renewable ones, does humanity have a chance for a long and happy existence on our planet. To implement cutting-edge developments, scientists around the world continue to carefully study the diverse properties of energy.