<Ul> <Li> Zeroth law of thermodynamics : If two systems are in thermal equilibrium with a third system , they are in thermal equilibrium with each other . This law helps define the concept of temperature . </Li> <Li> First law of thermodynamics : When energy passes , as work , as heat , or with matter , into or out from a system , the system 's internal energy changes in accord with the law of conservation of energy . Equivalently , perpetual motion machines of the first kind ( machines that produce work with no energy input ) are impossible . </Li> <Li> Second law of thermodynamics : In a natural thermodynamic process , the sum of the entropies of the interacting thermodynamic systems increases . Equivalently , perpetual motion machines of the second kind ( machines that spontaneously convert thermal energy into mechanical work ) are impossible . </Li> <Li> Third law of thermodynamics : The entropy of a system approaches a constant value as the temperature approaches absolute zero . With the exception of non-crystalline solids ( glasses ) the entropy of a system at absolute zero is typically close to zero , and is equal to the natural logarithm of the product of the quantum ground states . </Li> </Ul>
which law of thermodynamics is based on the conservation of energy law
First law of thermodynamics