First Law of Thermodynamics Statements

  • All we know that; heat and work are the two different types of energies which are responsible for the change in internal energy of the system.
  • The heat transfer between system occurs only when there will be some temperature difference occurs between system and the surrounding.
  • But work is also the form of energy which is not occured due to temperature difference.
  • The first law of thermodynamics is based in the transfer of energy from surrounding to system and how internal energy will change and how work will be done by the system.
  • First law of thermodynamics is nothing but the general law of conservation of energy.
  • It can be stated as follows.

Statement:

If ∆Q is the heat energy supplied to the system by the surrounding, ∆W is the work done by the system on the surrounding and if ∆U is the change in internal energy of the system then the first law of thermodynamics can be stated as mathematically,

∆Q = ∆U + ∆W

Thus, we can say that from this mathematical statement as the heat energy ∆Q supplied to the system is used partly to increase the internal energy ∆U of the system and remaining energy is used to work on the surrounding ∆W.

That means the total energy can neither be created nor be destroyed only it can be transferred from one form to another form.

Different statements of first law of thermodynamics:

  • The total internal energy of the isolated system means the system in which there is no exchange of either matter with the surrounding takes place is remains constant.
  • Energy can neither be created nor be destroyed but it can be only transferred from one form to another form only.
  • The total amount energy of the whole universe is always remains constant.
  • When there is some amount of energy get lost then same amount of energy in another form will be formed.

Applications:

  • First law of thermodynamics can be used to operate thermal engines in which mechanical energy is converted into heat energy and sometimes heat energy into the mechanical energy also.
  • Refrigerator also works on the principal of first law of thermodynamics.
  • In our body when our body temperature becomes more than normal then our body starts sweating and due to which some amount heat will be taken out from the body. This is also due to the first law of thermodynamics.
  • We all know that; we add ice cubes in drinks or juices because the heat from the drink or juice gets absorbed by the ice cubes and due to which they get melted and hence the drink or juice becomes colder than earlier. This happens only because of the first law of thermodynamics.
  • Thus, first law of thermodynamics is nothing but the law of conservation of energy.
Updated: April 14, 2022 — 12:51 pm

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