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Laws of Thermodynamics

Laws of Thermodynamics:

The Laws of Thermodynamics, in principle, describe the specifics for the transport of heat and work in thermodynamic processes.

Zeroeth Law of Thermodynamics

Two systems in thermal equilibrium with a third system are in thermal equilibrium to each other.This zeroeth law is sort of a transitive property of thermal equilibrium.
The transitive property of mathematics says that if A = B and B = C, then A = C. The same is true of thermodynamic systems that are in thermal equilibrium.

First Law of Thermodynamics

The change in a system's internal energy is equal to the difference between heat added to the system from its surroundings and work done by the system on its surroundings.

Mathematical Representation of the First Law

Physicists typically use uniform conventions for representing the quantities in the first law of thermodynamics. They are:

  • U1 (or Ui) = initial internal energy at the start of the process
  • U2 (or Uf) = final internal energy at the end of the process
  • delta-U = U2 - U1 = Change in internal energy (used in cases where the specifics of beginning and ending internal energies are irrelevant)
  • Q = heat transferred into (Q > 0) or out of (Q < 0) the system
  • W = work performed by the system (W > 0) or on the system (W < 0).

This yields a mathematical representation of the first law which proves very useful and can be rewritten in a couple of useful ways:
U2 - U1 = delta-U = Q - W
Q = delta-U + W


Second Law of Thermodynamics:

It is impossible for a process to have as its sole result the transfer of heat from a cooler body to a hotter one.

Third Law of Thermodynamics:

The third law of thermodynamics is essentially a statement about the ability to create an absolute temperature scale, for which absolute zero is the point at which the internal energy of a solid is precisely 0.

Various sources show the following three potential formulations of the third law of thermodynamics:

  • It is impossible to reduce any system to absolute zero in a finite series of operations.
  • The entropy of a perfect crystal of an element in its most stable form tends to zero as the temperature approaches absolute zero.
  • As temperature approaches absolute zero, the entropy of a system approaches a constant


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Physics Formulas
Molar Volume
Entropy
Angular Acceleration
Hydrostatic Presuure
Gravitation
Kinetic & Potential Energy
Enthalpy
Momentum
Thermal conductivity
Thermodynamic Coefficient
Ohm's Law
Molar Mass
Electric Charge
Resistance
Hooke's Law
Voltage
Impulse
Moment of Inertia
Newton's Law Of Motion
Density