The concept of energy
The Universe is in permanent transformation. From the atomic level to the vastness of the cosmos, from single-celled life to complex societies, there is a continuous movement of birth, development, and destruction of forms. Energy is the ability to produce these transformations and to do work.
Already in the fourth century BC, the Greek philosopher Aristotle called energy the ability to transform, produce changes, movement, and work. The modern concept of energy derives from that Aristotelian energy, which, over the years, has been systematically studied:
the laws that govern its transforming dynamics were established, the various forms of energy were defined and the energy sources that used and are used by societies in the course of their history.
forms of energy
Seven types of energy can be distinguished.
1. Electromagnetic energy
It is a form of radiant energy that propagates as a wave. It is the energy of solar radiation, which reaches the Earth’s surface as light and heat, and also that of cell phone, radio, or microwave waves.
According to the frequencies, electromagnetic waves have different properties. There is a particular frequency band that is the visible spectrum (between red and violet), which is the light that can be perceived. Electromagnetic waves propagate in a vacuum, so starlight can be seen and it is possible to communicate with a ship sent to Mars.
2. Chemical energy
This type of energy is always present in the matter since it is stored in atomic bonds. It can be found, for example, in firewood or fossil fuels. Chemical reactions and the heat they produce during combustion can be used to generate work or motion.
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3. Thermal energy
It is the energy relative to heat and one of the most common forms of energy. Heat is produced by atomic reactions, as in the Sun; by chemical reactions, such as when burning wood or paper; by friction, or by the metabolism of some living beings, such as mammals.
4. Electric power
It is the energy coming from the flow of electrons and electric fields. Electrons are atomic particles that have an electrical charge and that when moving in a conductor generate an electric current. This electrical current is transmitted through cables and reaches the sockets of homes. When you plug in an appliance (lights, computer, refrigerator, etc.), they connect with the electrical energy that makes them work.
5. Kinetic energy
It is the energy of movement. Every moving body has kinetic energy. The kinetic energy is greater than the speed and mass of the moving body. The flow of water in a river, the wind (which is moving air), a moving car, a ball hit by a racket, and people walking are examples of kinetic energy.
6. Nuclear energy
It is the energy that is in the nuclei of atoms and can be released during the process of fusion and fusion. Fusion is the union of two atomic nuclei of light atoms like hydrogen. When these nuclei meet, a large amount of energy is released in the form of heat.
Nuclear fusion involves the separation of the nucleus of a heavy atom such as uranium. When the nucleus is destroyed, a large amount of energy is released in the form of heat. In nuclear power plants, this is controlled and the heat is used to generate steam. The steam drives a turbine which generates electricity.
7. Gravitational energy
It is the energy of the force of gravity, the attractive force exerted between two bodies that have mass. Explains the fall of bodies and the movement of the planets. An example is the inevitable fall of an object when thrown into the air, the apple on Newton’s head, or the Earth revolving around the Sun.
The fundamental laws of energy
Energy has two fundamental laws.
- The first law says that the energy of the Universe is constant. When using energy, it does not disappear, but changes form. For example, in a car, the chemical energy of the fuel is transformed into movement, which is kinetic energy. In an iron, electrical energy is converted into heat. Photovoltaic cells transform the electromagnetic energy of the Sun into electrical energy.
- The second law says that no transformation is completely efficient, since while the total energy is conserved, something is lost. What is lost is known as useful energy. Energy efficiency is the amount of usable energy that is transformed into another form of energy. In reality, any energy conversion involves a loss of usable energy. The human body is a good example since it works like a machine whose fuel is food. Food provides the energy to move, breathe and think. However, only 5% of the ingested energy is used, the rest is dissipated as heat.
energy in modern societies
One of the distinctive features of modern societies is that they have developed from an energy regime based on fossil fuels. The use of coal, at the time of the Industrial Revolution, and then of hydrocarbons, in the 20th century, made possible an unprecedented increase in energy consumption.
Currently, there are three energy flows that shape and enable the contemporary way of life: food, fuel, and electricity. Life in large cities, the globalized economy, intensive transportation, instant communication, and food production for 7 billion inhabitants would not be possible without the high energy density of fossil fuels, the ease of transportation of refined products of oil, and the extraordinary flexibility of electricity.
Current societies are based on the high energy consumption made possible by hydrocarbons. Daily life relies heavily on energy, whether in the form of electricity, gas, or liquid fuels such as gasoline and diesel. We got up with the cell phone alarm, which was charged with electricity.
the same electricity that is used to light, listen to music, use the computer, the television, the air conditioning, and the refrigerator. Then, we heat the water formate or coffee using gas, which also feeds the heating, water heater, or hot water tank. Later, on the way to school, we take the bus that runs on diesel, which is a derivative of petroleum, just like the gasoline that cars use. Our whole life depends on energy.
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