While the somewhat whimsical example serves its superficial purpose, it is incorrect. The messy room is commonly used to illustrate the concept of entropy and illustrate the 2nd Law of Thermodynamics, but the simplification is egregiously misleading.Ī commonly observed daily life example of something constantly moving towards a state of randomness is a ‘kid’s room’. I wish they had a computer in every classroom dedicated to the khan academy.Ĭan you give a better simple real-life example of the 2nd Law than that of a messy room? Great article though, it only took me five hours to go through it, work out the problems, and research the meaning of the new vocabulary words.
Maybe I am reading it wrong, but which one? So, which is it? I hate for anyone else to go through my confusion. I thought I understood it to be -W if the system does the work "by the system". In focus, the statement of W being either negative, or positive are contradictory.
Q is positive if heat is added to the system, and negative if heat is removed W is positive if work is done by the system, and negative if work is done on the system." Then on the hyperlink under Sawan Patel's response: If work is done on the system, then W will be positive If work is done by the system, then W will be negative If heat flows into the system, then Q will be positive If heat flows out of the system, then Q will be negative start subscript, i, n, t, e, r, n, a, l, end subscript = Q + W) let’s be ‘very very’ clear of the following norms. On the 9th paragraph, under What is internal energy heading: Their temperatures are T 1 _1 1 start subscript, 1, end subscript, T 2 _2 2 start subscript, 2, end subscript and T 3 _3 3 start subscript, 3, end subscript respectively. Let’s assume we have three systems - system 1, system 2 and system 3. In other words, now the two systems are in thermal equilibrium with each other and there is no more heat flow taking place between the two systems. Heat flow stops when the two systems reach the same temperature. Here, heat flows from the system at a higher temperature (bowl of soup) to the system at a lower temperature (freezer). Even if you are familiar with this concept, what you may not realize is that this is an excellent example of thermal equilibrium. And you also probably know that the soup will continue to cool down until it reaches the same temperature as the freezer. The soup will, of course, start cooling down with time. For instance, let's say you have a bowl of hot soup and you put it in the freezer. Thermal equilibrium is a concept that is so integral to our daily lives. In simple words, thermal equilibrium means that the two systems are at the same temperature. When two systems are in contact with each other and no energy flow takes place between them, then the two systems are said to be in thermal equilibrium with each other. Let’s first define what ‘thermal equilibrium’ is.
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