empirical facts in the realm of physics. Fundamental laws of Physics that are applicable to other sciences aswell. There are three fundamental laws recognised. ## Terminology **Heat(Q)** first way to add or remove energy from a system in form of heat, driven by temperature differences. **work(W)** second way to add or remove energy from a system, describes the process in form of force exerted through a distance **internal Energy(U)** sum of kinetic and potential energies of a system's atoms and molecules. **pressure(P)** $P=\frac{F}{A}$ Where P is pressure, F is force and A is Area. Describes Pressure, which consists of a force being applied to an Area. For example, see [[../../Concepts/Wissenschaft/Pascal (unit|Pascal (unit|[unit)]]]].md) formular: $Pa=\frac{N}{m^2}$ **system** Describes the current scope of the section of the universe we are currently observing. This can be a chemical reaction, a car or even a planet. **microstate** one microstate describes the configuration a System can be in. It describes the precise positions and momenta of all the individiual particles or components that make up the system. Each Microstate has a certain probability of occuring during the course of the system's thermal fluctuations **macrostate** related to the microstate, refers to more general values like temperature, pressure, volume and density. **Entropy** Measure of Disorder of a system. Or more precisely it's related to the number of microstates in which a system can exist. Describes how much Energy is not available to do work. ![[_media/Laws of thermodynamics2024-03-16.png|300]] ## Zeroeth law >"Objects which are in thermal contact with each other will always reach the same temperature and therefore reach [[../../Concepts/Wissenschaft/Thermal equilibrium.md]]" ## First law >"Conservation of energy: energy cannot be created or destroyed" >$ΔU=Q−W$. In an isolated system with constant amount of matter the sum of all forms of energy is constant. The most famous contradiction to this Law are [[perpetual motion machines]] ## Second law >"The total entropy of a system either increases or remains constant in any spontaneous process; it never decreases" It is often misunderstood that the second law of thermodynamics means the entropy can never decrease at any location. But this is not true, as long as entropy in the system overall increases this is still valid. **Example** >In another example, crystals can form from a salt solution as the water is evaporated. Crystals are more orderly than salt molecules in solution; however, vaporized water is much more disorderly than liquid water. The process taken as a whole results in a net increase in disorder. ## Third law >"as the temperature of a system approaches absolute zero, its [entropy](https://youtu.be/gOWt_Hq3yrE "Entropy") becomes constant, or the change in entropy is zero." **concept of a "perfect crystal"** The perfect crystal describes the idea of a crystal that is perfectly ordered in absolute 0 temperature([[../../Concepts/Wissenschaft/Kelvin (unit|Kelvin (unit|[unit)]]]].md)). It therefore posesses no entropy. ## 🔗Resources - https://en.wikipedia.org/wiki/Laws_of_thermodynamics - https://en.wikipedia.org/wiki/First_law_of_thermodynamics - https://openstax.org/books/physics/pages/12-1-zeroth-law-of-thermodynamics-thermal-equilibrium - https://www.chadsprep.com/chads-general-chemistry-videos/3-laws-of-thermodynamics-definition/ - https://en.wikipedia.org/wiki/Microstate_(statistical_mechanics)