Joule (unit J) – Energy Unit

Energy Units

Energy is generally defined as the potential to do work or produce heat. This definition causes  the SI unit for energy is the same as the unit of work – the joule (J). Joule is a derived unit of energy and it is named in honor of James Prescott Joule and his experiments on the mechanical equivalent of heat. In more fundamental terms, 1 joule is equal to:

1 J = 1 kg.m2/s2

Since energy is a fundamental physical quantity and it is used in various physical and engineering branches, there are many energy units in physics and engineering.

Joule – Energy Units

Joule (unit: J). Joule  is a derived unit of energy. It is equal to the energy transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre.

    • 1 joule = 0.239 Calories
    • 1 joule = 9.48 x 10-4 BTU
    • 1 joule = 2.778 x 10-7 kWh

    conversion - joule, calorie, kilowatthour - energy units

    Examples of Energy of 1 Joule

    One joule in everyday life and in science corresponds to approximately:

    • The kinetic energy of an object with mass 1 kg moving at √2 ≈ 1.4 m/s.
    • The kinetic energy of a 50 kg object (e.g. human) moving very slowly – approximately 0.72 km/h.
    • The energy required to lift a medium-size apple (100 g) 1 meter vertically from the surface of the Earth.
    • The heat required to raise the temperature of 1 g of water by 0.24 °C.
    • The heat required to evaporate of 0.00044 g of liquid water at 100°C.
    • The amount of electricity required to light a 1 watt LED for 1 s.
    • Is released by approximately 3.11010 fissions in a nuclear reactor.
     
    References:
    Reactor Physics and Thermal Hydraulics:
    1. J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).
    2. J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.
    3. W. M. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1.
    4. Glasstone, Sesonske. Nuclear Reactor Engineering: Reactor Systems Engineering, Springer; 4th edition, 1994, ISBN: 978-0412985317
    5. Todreas Neil E., Kazimi Mujid S. Nuclear Systems Volume I: Thermal Hydraulic Fundamentals, Second Edition. CRC Press; 2 edition, 2012, ISBN: 978-0415802871
    6. Zohuri B., McDaniel P. Thermodynamics in Nuclear Power Plant Systems. Springer; 2015, ISBN: 978-3-319-13419-2
    7. Moran Michal J., Shapiro Howard N. Fundamentals of Engineering Thermodynamics, Fifth Edition, John Wiley & Sons, 2006, ISBN: 978-0-470-03037-0
    8. Kleinstreuer C. Modern Fluid Dynamics. Springer, 2010, ISBN 978-1-4020-8670-0.
    9. U.S. Department of Energy, THERMODYNAMICS, HEAT TRANSFER, AND FLUID FLOW. DOE Fundamentals Handbook, Volume 1, 2 and 3. June 1992.

    See above:

    Energy