energy

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.

• Types of Energy

  • The various types of energy include kinetic, potential, and chemical energy.
  • The potential energy stored in molecules can be converted to chemical energy, which can ultimately be converted to kinetic energy, enabling an organism to move.
  • Energy associated with objects in motion is called kinetic energy.
  • The jet engines are converting potential energy in fuel to the kinetic energy of movement.
  • This type of potential energy is called chemical energy, and like all potential energy, it can be used to do work.

• 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.

• The Role of Energy and Metabolism

  • All organisms require energy to complete tasks; metabolism is the set of the chemical reactions that release energy for cellular processes.
  • Plants convert light energy from the sun into chemical energy stored in molecules during the process of photosynthesis.
  • Some of these chemical reactions are spontaneous and release energy, whereas others require energy to proceed.
  • Energy is needed to perform heavy labor and exercise, but humans also use a great deal of energy while thinking and even while sleeping.
  • Just as energy is required to both build and demolish a building, energy is required for both the synthesis and breakdown of molecules.

• Free Energy

  • Free energy, called Gibbs free energy (G), is usable energy or energy that is available to do work.
  • Since chemical reactions release energy when energy-storing bonds are broken, how is the energy associated with chemical reactions quantified and expressed?
  • A measurement of free energy is used to quantitate these energy transfers.
  • In other words, Gibbs free energy is usable energy or energy that is available to do work.
  • Exergonic reactions release energy; endergonic reactions require energy to proceed.

• Activation Energy

  • Activation energy is the energy required for a reaction to occur, and determines its rate.
  • Why would an energy-releasing, negative ∆G reaction actually require some energy to proceed?
  • Since these are energy-storing bonds, they release energy when broken.
  • Free energy diagrams illustrate the energy profiles for a given reaction.
  • This figure implies that the activation energy is in the form of heat energy.

• 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

• Pressure and Free Energy

  • Gibbs free energy measures the useful work obtainable from a thermodynamic system at a constant temperature and pressure.
  • Just as in mechanics, where potential energy is defined as capacity to do work, similarly different potentials have different meanings.
  • The Gibbs free energy is the maximum amount of non-expansion work that can be extracted from a closed system.
  • Gibbs energy (also referred to as ∆G) is also the chemical potential that is minimized when a system reaches equilibrium at constant pressure and temperature.
  • Therefore, Gibbs free energy is most useful for thermochemical processes at constant temperature and pressure.