THERMODYNAMICS

1.) Which of the following represents the first law of thermodynamics? Explain.  - After falling down the hill, a ball's kinetic energy plus heat energy equals the initial potential energy - If a refrigerator is unplugged, eventually everything inside of it will return to room temperature - Two systems in equilibrium with a third system are in equilibrium with each other - The specific heat of an object explains how easily it changes temperatures - While melting, an ice cube remains at the same temperature   ANS: After falling down the hill, a ball's kinetic energy plus heat energy equals the initial potential energy 2.)  A gas in a closed container is heated, causing the lid of the container to rise. The gas performs 3J of work to raise the lid, such that is has a final total energy of 15J. How much heat energy was added to the system?     ANS. 18J 3.) A gas in a closed conta...

The First Law of Thermodynamics, also known as the Law of the Conservation of Energy , says that energy cannot be created or destroyed, it can only change form. Energy comes in a ton of different forms, including: Energy comes in a variety of different forms. ( Image source ) Energy is not created or destroyed; it simply changes from one form to another. Turning on a light switch does not create energy, it simply converts electrical energy into radiant energy (light) and thermal energy (heat). Practical examples of the transformation of energy in action. ( Image source) Within the First Law are three related concepts – work, heat, and internal energy.   Heat  is the transfer of thermal energy between two systems .   Work   is the force that transfers energy between a system and its surroundings. By producing work either within a system or outside of it, you create heat. Then there’s  i nternal energy , which is all the energy within a...

The Third Law of Thermodynamics says that a perfect crystalline structure at absolute zero temperatures will have zero disorder or entropy.   However, if there is even the smallest hint of imperfection in this crystalline structure, then there will also be a minimal amount of entropy. This law gets a little strange though, because even at zero Kelvin there is still some atomic movement happening, so it’s a bit theoretical. Regardless, this law allows us to understand that as the entropy of a system approaches a temperature of absolute zero , the entropy present within a system decreases . The Third Law of Thermodynamics. ( Image source ) ZEROTH LAW: It says that if two systems are in thermal equilibrium with a third system, then the first two systems are also in thermal equilibrium with one another.  Using our good old Transitive Property of Equality:  If System A is in balance with System C a nd System B is in balance with System C, t he...

The Second Law of Thermodynamics, also known as the Law of Increased Entropy , says that over time the state of disorganization or  entropy  in a system will always increase. What do we mean by this? Take this example – why does your desk always get messier as the week progresses? Or more importantly, why doesn’t your office go from messy to clean without you having to do work on it? This is the arrow of time in thermodynamics. As time increases, so too does disorganization. This phenomenon happens in any system. Over time, usable energy will eventually give way to unusable energy. While energy cannot be created or destroyed according to the First Law, it can change form a useful state to a less-useful state, like thermal energy (heat). Over time, every system moves from a state of low to high entrop Image source ) In our light bulb example again, the longer we leave our light bulb on, converting electrical energy into radiant energy, the more usable energ...