Internal Energy

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Equation / Last modified by KurtHeckman on 2019/01/11 15:05
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Dasha.Internal Energy

The Internal Energy calculator computes the total change in internal energy of a system based on heat exchanged (q) and the work (w) done by or on the system.

INSTRUCTIONS: Choose the preferred units and enter the following:

  • (q) - This is the heat exchanged between a system and its surroundings in units of (Joules)
  • (w) - This is the work done by or on the system in units of (Joules)

Internal Energy (ΔU): The calculator returns the total change in internal energy of a system in units of (Joules).  However this can be automatically converted to compatible units via the pull-down menu.

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The Science

The Internal energy[1] equation calculates the amount of energy is absorbed or released by the system. This equation is also known as the first law of thermodynamics. The first law of thermodynamics is often called the Law of Conservation of Energy[3].This law suggests that Energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy and matter in the Universe remains constant, merely changing from one form to another. The First Law of Thermodynamics (Conservation) states that energy is always conserved, it cannot be created or destroyed. In essence, energy can be converted from one form into another.

The Math

The formula for Internal energy is:

     ΔU = q+w


When work is done by the system then work will be negative and positive when work is done on to the system. When heat is negative, then it is released from the system. 

Related Topics

Supplement Material



[2]Whitten, et al. 10th Edition. Pp.571



This equation, Internal Energy, is listed in 2 Collections.