You consume every day energy, e.g. B. when you go to school, when you go for a ride on your bike in the afternoon, or even just when you try to solve your physics homework.
energy can in many forms exist and also in a different form transformed will.
Energy: unit, definition and symbol
energy is one physical size. It not only plays a major role in physics, but also in chemistry, biology and many other areas – including in everyday life.
For example, you can find energy in many places in your everyday life, be it the sun, an oven or a granola bar. Perhaps you are reading this text on a computer or mobile phone – both are powered by a specific form of energy: the electrical energy.
energy describes one’s ability physical systems work to perform warmth or radiation to deliver.
That symbol of energy is that E.
the Unit of energy is that joules:
Depending on the form of energy you will find the energy with different indices.
But beware! There is another important quantity in physics that is denoted by an E: the electric field. Therefore, always pay attention to the context in which you encounter this symbol. You can make a simple distinction if the symbol has a descriptive index, e.g. B. Eel or Epot . Then it is mostly about forms of energy and not about the electric field. As a rule, the electric field has no descriptive index, at most a number, such as E1 and E2.
Sometimes you will also find another unit of energy: the kilocalorie kcal. However, this unit of energy is rarely used for physical considerations. But you can find them on your muesli bar, for example: Food are always provided with an energy specification in kilocalories. You can just look at a piece of food packaging in your home. There you will find this unity of energy.
Forms of energy (+ table) and energy conversion
Energy has many to formthat can occur in different situations. They are calculated in different ways, but they can all be intertwined transformed will. Below you will find information about the energy conversion and an overview of the most important forms of energy.
Conservation & Conversion of Energy
An important physical principle is that conservation of energy. energy can in one closed system not lost walk.
A closed system is a system in which no material exchange takes place with the environment. You can think of it as a closed container, which may be deformable and which can give off heat, but from which no matter can escape.
For example, a thermos is a closed system. The tea or coffee cannot get out, but after a while it gets cold because the heat is released through the bottle wall.
So plotted against a time axis, the energy of a system would always be same (constant).
Of the law of conservation of energy states that the total energy one closed systems temporal constant is. This means that no energy can be created or destroyed.
You can find more details and examples on the subject of energy conservation in thermodynamic systems in the articles on the subject of thermodynamics.
So the energy is one conservation size. This term indicates that size is conserved in a closed system.
energy conversion? What does that mean? Energy comes in different forms and cannot be destroyed. So the question arises, what happens to the energy that a body gives off if it is not lost?
If a body releases energy, then its being changes energy content. But in system the energy is conserved, it may now be in one others shape before.
forms of energy
Energy is first differentiated into basic forms: mechanical, Electric, inner energy and radiant energy. Internal energy can be subdivided into chemical energy and thermal energy. The mechanical energy has z. B. the sub-forms potential energy and kinetic energy. You can see examples of the different forms of energy in the following overview:
Potential Energy – Elevation/Attitude energy
the potential Energy is also often referred to as altitude energy or potential energy designated. As the name suggests, it is a form of energy that bodies possess when they are in a certain position Height condition.
A body of Dimensions m owns in one place with the location factor G the potential energy epotwhen he is in a Height H above the defined zero level (H = 0).
So whether a body has potential energy depends on its height above the zero level away. The zero level is where . So first the zero level has to be defined before a statement about the potential energy can be made.
The zero level is in many cases the floor. But you can also do your zero level different define. It is only important that the zero level is specified.
An apple lying on a table has zero level potential energy relative to the ground. However, if you set your zero level as the surface of the table, the apple has no potential energy since it is the same height as the zero level.
You can find more on this topic, such as examples and calculations, in the article «Potential Energy».
Kinetic energy – energy of motion
the kinetic energy will too kinetic energy called because they have the energy of a self moving body describes.
A body of Dimensions m owns one kinetic energy Ekinwhen he is with a speed v emotional.
Kinetic energy appears wherever things move. You will often encounter kinetic energy in your everyday life too: yours bicycle or yours automobile both have kinetic energy when they are pedaling or motor-driven and therefore moving. You too have To run for example a kinetic energy.
Thermal energy – thermal energy
Any fabric with a temperature above that absolute zero point owns thermal Energy. She hangs with the disorderly movement the particle inside him together.
A body of Dimensions m with the heat capacity c owns thermal energy ether, if he one temperature Has.
Assuming you have one ice cubes in front of you. This ice cube has thermal energy because it has a temperature above the absolute zero point Has.
Of the absolute zero point () is the lowest possible temperature. At this point all particles come to the standstilland therefore there can be no lower temperature.
If your ice cube now melts, his increases temperature and with it his thermal Energy. The water molecules now detach from the lattice and can freer move. If you put the melted ice cubes, i.e. the water, in a pot heatedthe molecules gain more and more free space. So you always have more space to yourself disordered to be able to move. Therefore, the thermal energy of the water continues to increase.
You can find more about this in the article «Thermal energy».
Electrical power
Electric Energy is everywhere. She’s good at it saved and transported and is therefore used for many applications. A typical example for the storage of electrical energy in everyday life is a battery.
Electric energy will by means of electricity transferred and in electrical or magnetic fields saved. Depending on the form of storage, the energy is calculated in different ways:
- in the electrical Field: Is there one tension u at the capacitor capacity C on, it contains the electrical energy El.
- in the magnetic Field: A coil with the inductance Lcontains the electrical energy Elif with the electricity I is flowed through.
Electrical energy is mostly used in power plants generated. Some forms of these power plants include nuclear power plants, coal-fired power plants, hydroelectric power plants or wind turbines. In all these power plants, an existing energy is electrical energy transformed.
For example, in one hydroelectric power station the altitude of the water (potential energy) used to drive a turbine with the falling water. in one coal-fired power station becomes the coal burned and the resulting one thermal Energy is converted into electrical energy.
Electrical energy, as we know it from our everyday lives, usually comes from a power plant that has the ability to energy conversion uses.
You can learn more about this in the articles «Electric Field Energy», «Magnetic Field Energy» and «Power Plants».
Forms of energy at a glance
Here you will find an overview of the forms of energy with the most important information:
Energy carrier definition & table
Where does the energy come from that we use to run our cars, that we use to generate electricity for our lamps? We get this energy from so-called energy carriers.
energy sources are substances that contain energy to save can and their energy content then through energy conversion usable can be made. Here, in primary and secondary different energy carriers.
primary You can find energy sources directly in nature. There is there for one regenerative Energy carriers, that is, they are infinite resources such as sunlight or wind. On the other hand there is fossil energy sources. their occurrence is limited. These include, for example, oil, natural gas and coal. Primary energy is also that atomic energy. Their energy sources are radioactive substances such as uranium.
secondary Energy sources must first won will. Here, primary energy sources are broken down and converted into a secondary energy source transformed. This process is also called refining. For example, crude oil can be converted into petrol and diesel.
Here you will find an overview of the energy sources and to which category they belong.
Primary energy sourcesSecondary energy sourcesrenewable
- sunlight
- wind
- water at high altitude
- tides of the sea
- Wood (only as fast as it grows back)
- biomass
- geothermal
- hydrogen
- Electricity from solar/wind/water energy
- biogas
fossil
- diesel
- petrol
- Electricity from oil/gas/coal
- fuel oil
- briquettes
atomic energy
(there are no secondary energy sources here)
Energy, energy sources and forms of energy – the most important things
- Energy exists in different to formwhich also intertwine transformed can become.
- For the conversion applies the law of conservation of energy: Energy cannot be destroyed or created.
- energy is the Capability one physical systems work to perform warmth or radiation to deliver.
- That symbol of energy is that E, their Unit the joule: .
- potential A body has energy altitude above a defined zero level. Your formula is:
- kinetic Energy owns itself moving Body. The formula of this form of energy is:
- thermal All bodies possess an absolute energy temperature T>0K. Your formula is:
- Electric Energy is in an electric or magnetic Field saved. Depending on the type of storage, its formula is:
- energy is in energy carriers saved. The…