In physics, mechanical energy describes the potential energy and kinetic energy present in the components of a mechanical system. A magnet levitating above a high-temperature superconductor demonstrates the Meissner effect. ... Potential energy can be thought of as energy stored within a physical system. ... The kinetic energy of an object is the extra energy which it possesses due to its motion. ...

Related concepts

When a given amount of mechanical energy is transferred (such as when throwing a ball, lifting a box, crushing a can, or stirring a beverage) it is said that this amount of mechanical work has been done. Both mechanical energy and mechanical work are measured in the same units as energy in general. It is usually said that a component of a system has a certain amount of "mechanical energy" (i.e. it is a state function), whereas "mechanical work" describes the amount of mechanical energy a component has gained or lost. In physics, mechanical work is the amount of energy transferred by a force. ... In thermodynamics, a state function, or state quantity, is a property of a system that depends only on the current state of the system, not on the way in which the system got to that state. ...

The conservation of mechanical energy is a principle which states that under certain conditions, the total mechanical energy of a system is constant. This rule does not hold when mechanical energy is converted to other forms, such as chemical, nuclear, or electromagnetic. However, the principle of general conservation of energy is so far an unbroken rule of physics - as far as we know, energy cannot be created or destroyed, only changed in form. In physics, mechanical energy is one of several forms of energy. ... Look up conservation of energy in Wiktionary, the free dictionary. ...

Simplifying assumptions

Scientists make simplifying assumptions to make calculations about how mechanical systems react. For example, instead of calculating the mechanical energy separately for each of the billions of molecules in a soccer ball, it is easier to treat the entire ball as one object. This means that only two numbers (one for kinetic mechanical energy, and one for potential mechanical energy) are needed for each dimension (for example, up/down, north/south, east/west) under consideration. 2-dimensional renderings (ie. ...

To calculate the energy of a system without any simplifying assumptions would require examining the state of all elementary particle(s) and considering all four [fundamental interaction]s). This is usually only done for very small systems, such as those studied in [[particle physics].

Distinguished from other types of energy

The classification of energy into different "types" often follows the boundaries of the fields of study in the natural sciences.

• Chemical energy, the kind of potential energy stored in chemical bonds; studied in chemistry
• Nuclear energy, energy stored in interactions between the particles in the atomic nucleus; studied in nuclear physics
• Electromagnetic energy, in the form of electric charges, magnetic fields, and photons; from the study of electromagnetism
• Various forms of energy in quantum mechanics; for example, the energy levels of electrons in an atom

In certain cases, it can be unclear what counts as "mechanical" energy. For example, is the energy stored in the structure of a crystal "mechanical" or "chemical"? Scientists generally use these "types" as convenient labels which clearly distinguish between different phenomena. It is not scientifically important to decide what is "mechanical" energy and what is "chemical". In these cases, usually there is a more specific name for the phenomenon in question. For example, in considering two bonded atoms, there are energy components from vibrational motion, from angular motions, from the electrical charge on the nuclei, secondary electromagnetic considerations like the Van der Waals force, and quantum mechanical contributions concerning the energy state of the electron shells. Potential energy can be thought of as energy stored within a physical system. ... In chemistry, a chemical bond is the force which holds together atoms in molecules or crystals. ... For other uses, see Chemistry (disambiguation). ... This article concerns the energy stored in the nuclei of atoms; for the use of nuclear fission as a power source, see Nuclear power. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... Nuclear physics is the branch of physics concerned with the nucleus of the atom. ... Electrical energy or Electromagnetic energy is a form of energy present in any electric field or magnetic field, or in any volume containing electromagnetic radiation. ... In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... Electromagnetism is the physics of the electromagnetic field: a field which exerts a force on particles that possess the property of electric charge, and is in turn affected by the presence and motion of those particles. ... For a less technical and generally accessible introduction to the topic, see Introduction to quantum mechanics. ... A quantum mechanical system can only be in certain states, so that only certain energy levels are possible. ... For other uses, see Electron (disambiguation). ... In chemistry, the term van der Waals force originally referred to all forms of intermolecular forces; however, in modern usage it tends to refer to intermolecular forces that deal with forces due to the polarization of molecules. ...

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