Energy is what makes life possible not only on our planet, but also in the Universe. However, it can be very different. So, heat, sound, light, electricity, microwaves, calories are different types of energy. For all the processes taking place around us, this substance is necessary. Most of the energy that exists on Earth receives from the Sun, but there are other sources of it. The sun transfers it to our planet as much as 100 million of the most powerful power plants would produce at the same time.
What is energy?
The theory put forward by Albert Einstein studies the relationship between matter and energy. This great scientist was able to prove the ability of one substance to turn into another. At the same time, 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. She is the one who stands forthe concept of a force capable of moving a body or giving it new properties. What does the term "energy" mean? Physics is a fundamental science to which many scientists from different eras and countries devoted their lives. Even Aristotle used the word "energy" to refer to 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 called "Physics".
In the now generally accepted sense, this term was coined by the English physicist Thomas Young. This momentous event took place back in 1807. In the 50s of the XIX century. the English mechanic William Thomson was the first to use 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 one form into another.
Measurements and designations
The amount of energy is measured in joules (J). This special unit, depending on the type of energy, may have different designations, for example:
- W is the total energy of the system.
- Q - thermal.
- U – potential.
Types of energy
There are many different types of energy in nature. 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 the so-called "dark" energy. Each of the previously listed types of this substance has its own characteristics. For example, sound energy can be transmitted using waves. They contribute to the vibration of the eardrums in the ear of people and animals, thanks to which sounds can be heard. In the course of various chemical reactions, the energy necessary for the life of all organisms is released. Any fuel, food, accumulators, batteries are the storage of this energy.
Our star gives the Earth energy in the form of electromagnetic waves. Only in this way can it overcome the expanses of the Cosmos. Thanks to modern technology, such as solar panels, we can use it to the greatest effect. Excess unused energy is accumulated in special energy storage facilities. Along with the above types of energy, thermal springs, rivers, ocean ebbs and flows, biofuels are often used.
Mechanical Energy
This kind of energy is studied in the branch of physics called "Mechanics". It is denoted by the letter E. It is measured in joules (J). What is this energy? The 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 calledkinetic (denoted by Ek), and the energy due to the interaction of bodies or external fields is called potential (Ep). The sum of motion 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, it is necessary to calculate the work required to transfer the body from the zero state to this state. Moreover, the more work, the more energy the body will have in this state.
Separation of species according to different criteria
There are several kinds of energy sharing. According to various criteria, it is divided into: external (kinetic and potential) and internal (mechanical, thermal, electromagnetic, nuclear, gravitational). Electromagnetic energy, in turn, is divided into magnetic and electric, and nuclear energy is divided into the energy of weak and strong interactions.
Kinetic
Any moving bodies are distinguished by the presence of kinetic energy. It is often called that - driving. The energy of a body that is moving is lost when it slows down. Thus, the faster the speed, the greater the kinetic energy.
When a moving body comes into contact with a stationary object, a part of the kinetic one is transferred to the latter, setting it in motion. The kinetic energy formula is as follows:
In words, this formula can be expressed as follows: the kinetic energy of an object is equal tohalf the product of its mass times 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 potential and acquires kinetic. In this case, the value of these two types will be equivalent. In the gravitational field of our planet, the potential energy formula will look like this:
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, 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 the field forces. Sometimes it is called the coordinate function, which is a term in the system's Langrangian (the Lagrange function of a dynamical system). This system describes their interaction.
Potential energy is equated to zero fora 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".
The law of conservation of energy
One of the most basic postulates of physics is the law of conservation of energy. According to him, energy does not appear from anywhere and does not disappear anywhere. It constantly changes from one form to another. In other words, there is only a change in energy. So, for example, the chemical energy of a flashlight battery is converted into electrical energy, and from it into light and heat. Various household appliances turn electrical energy into light, heat or sound. Most often, the end result of the change is heat and light. After that, the energy goes into the surrounding space.
The law of energy can explain many physical phenomena. Scientists argue that its total volume in the universe constantly remains unchanged. No one can create energy anew or destroy it. Developing one of its types, people use the energy of fuel, falling water, an atom. At the same time, one of its forms 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 conjugate energy. In other words, energy is conserved due to the fact that the laws of physics do not differ at different times.
Energy Features
Energy is the ability of a body to do work. In closedphysical systems, it is preserved throughout the entire time (as long as the system is closed) and is one of the 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 appropriate when the physical system is homogeneous in time.
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 because it is a single-valued function of the state of the system. Whenever a system finds itself in a given state, its internal energy has its inherent value, regardless of the history of the system's existence. The change in internal energy during the transition from one physical state to another is always equal to the difference between its values in the final and initial states.
Internal energy of gas
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 a gas) is the sum of the kinetic energies of its particles. This takes into account the number of degrees of freedom, which is the number of independent variables that determine the position of the molecule in space.
Energy use
Every year humanity consumes more and more energy resources. Most often for energy,necessary for lighting and heating our homes, the operation of vehicles and various mechanisms, fossil hydrocarbons such as coal, oil and gas are used. They are non-renewable resources.
Unfortunately, only a tiny fraction of our planet's energy comes from renewable resources such as water, wind and the sun. To date, their share in the energy sector is only 5%. Another 3% 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 1024;
- gas and oil energy – 2 x 10 23;
- internal heat of the planet - 5 x 1020.
Annual value of the Earth's renewable resources:
- solar energy - 2 x 1024;
- wind - 6 x 1021;
- rivers - 6, 5 x 1019;
- sea tides - 2.5 x 1023.
Only with a timely transition from the use of non-renewable energy reserves of the Earth to renewable ones, humanity has 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 various properties of energy.
