energy

(noun)

A quantity that denotes the ability to do work and is measured in a unit dimensioned in mass × distance²/time² (ML²/T²) or the equivalent.

Related Terms

Examples of energy in the following topics:

  • Other Forms of Energy

    • Electric Energy: This is energy that is from electrical potential energy, a result of Coulombic forces.
    • Magnetic Energy: Technically magnetic energy is electric energy; the two are related by Maxwell's equations.
    • In each of the aforementioned forms, energy exists as either kinetic energy, potential energy, or a combination of both.
    • For example, luminous energy is radiant energy.
    • A brief overview of energy, kinetic energy, gravitational potential energy, and the work-energy theorem for algebra-based physics students.

  • Internal Energy

    • The internal energy of a system is the sum of all kinetic and potential energy in a system.
    • The internal energy is the energy required to create a system, excluding the energy necessary to displace its surroundings.
    • Internal energy has two components: kinetic energy and potential energy.
    • The kinetic energy portion of internal energy gives rise to the temperature of the system.
    • Express the internal energy in terms of kinetic and potential energy

  • World Energy Use

    • World energy consumption is the total amount of energy used by all humans on the planet (measured on a per-year basis).
    • Potential renewable energy sources include: solar energy at 1600 EJ (444,000 TWh), wind power at 600 EJ (167,000 TWh), geothermal energy at 500 EJ (139,000 TWh), biomass at 250 EJ (70,000 TWh), hydropower at 50 EJ (14,000 TWh) and ocean energy at 1 EJ (280 TWh).
    • In the US, only 10% of energy comes from renewable sources (mostly hydroelectric energy).
    • While renewable energy development makes up a only small percentage of the field, strides are being made in natural energy, particularly wind energy.
    • In China, two thirds of the energy used each year is from commercial coal energy.

  • Energy Transformations

    • Energy transformation occurs when energy is changed from one form to another.
    • However, when the pendulum is at its lowest point, all of its energy exists in the form of kinetic energy.
    • For example, the theoretical limit of the energy efficiency of a wind turbine (converting the kinetic energy of the wind to mechanical energy) is 59%.
    • This corresponds to zero kinetic energy and thus all of the energy of the pendulum is in the form of potential energy.
    • These figures illustrate the concepts of energy loss and useful energy output.

  • Rotational Kinetic Energy: Work, Energy, and Power

    • The rotational kinetic energy is the kinetic energy due to the rotation of an object and is part of its total kinetic energy.
    • Rotational kinetic energy is the kinetic energy due to the rotation of an object and is part of its total kinetic energy .
    • Note the close relationship between the result for rotational energy and the energy held by linear (or translational) motion:
    • Therefore, it has a rotational kinetic energy of 2.138×1029 J.
    • Express the rotational kinetic energy as a function of the angular velocity and the moment of inertia, and relate it to the total kinetic energy

  • Problem Solving With the Conservation of Energy

    • To solve a conservation of energy problem determine the system of interest, apply law of conservation of energy, and solve for the unknown.
    • When they start rising, the kinetic energy begins to be converted to gravitational potential energy ($PE_g$).
    • If you know the potential energies ($PE$) for the forces that enter into the problem, then forces are all conservative, and you can apply conservation of mechanical energy simply in terms of potential and kinetic energy.
    • If you know the potential energy for only some of the forces, then the conservation of energy law in its most general form must be used:
    • When they start rising, the kinetic energy begins to be converted to gravitational potential energy.

  • Internal Energy of an Ideal Gas

    • Internal energy is the total energy contained by a thermodynamic system, and has two major components: kinetic energy and potential energy.
    • In thermodynamics, internal energy is the total energy contained by a thermodynamic system.
    • Internal energy has two major components: kinetic energy and potential energy.
    • Therefore, we will disregard potential energy and only focus on the kinetic energy contribution to the internal energy.
    • In this case, the kinetic energy consists only of the translational energy of the individual atoms.

  • What is Potential Energy?

    • Potential energy is the energy difference between the energy of an object in a given position and its energy at a reference position.
    • This work is stored in the force field as potential energy.
    • The more formal definition is that potential energy is the energy difference between the energy of an object in a given position and its energy at a reference position.
    • For example, the work of an elastic force is called elastic potential energy ; work done by the gravitational force is called gravitational potential energy; and work done by the Coulomb force is called electric potential energy.
    • In the case of a bow and arrow, the energy is converted from the potential energy in the archer's arm to the potential energy in the bent limbs of the bow when the string is drawn back.

  • Gravity

    • Gravitational energy is the potential energy associated with gravitational force, as work is required to move objects against gravity.
    • Gravitational energy is the potential energy associated with gravitational force (a conservative force), as work is required to elevate objects against Earth's gravity.
    • The potential energy due to elevated positions is called gravitational potential energy, evidenced, for example, by water held in an elevated reservoir or behind a dam (as an example, shows Hoover Dam).
    • (The surface will be the zero point of the potential energy. ) We can express the potential energy (gravitational potential energy) as:
    • Hoover dam uses the stored gravitational potential energy to generate electricity.

  • Conservation of Mechanical Energy

    • Conservation of mechanical energy states that the mechanical energy of an isolated system remains constant without friction.
    • Though energy cannot be created nor destroyed in an isolated system, it can be internally converted to any other form of energy.
    • The work-energy theorem states that the net work done by all forces acting on a system equals its change in kinetic energy (KE).
    • This equation is a form of the work-energy theorem for conservative forces; it is known as the conservation of mechanical energy principle.
    • The total kinetic plus potential energy of a system is defined to be its mechanical energy (KE+PE).