The Law of Thermodynamics

The Laws Of Thermodynamics

There are 3 laws of thermodynamics however there is a zeroth law as well (Don't forget that!)

0th law;

If two systems are in thermal equilibrium independently system, they must be a thermal equilibrium with each other. they must be in thermal equilibrium with each other.

1st Law;

When energy passes, as work as heat, or with matter into or out from a system, its internal energy changes in accord with the law of conservation of energy.

• In terms of The System models this law would be used as an approach to pressure drop in open system or how much energy is required by an organism.
• In a nutshell first law simply means conservation of energy, or it states that energy is getting transformed from one form to another form.

Open System

Figure 1; representation of an open system (contaminator) with the equation by each side to work out the input and output

Closed System

Figure 2; shows how the cylinder is a closed system and is in the as the Q is it input and W is the Weight

it will increase by a quantity Q, because it is absorbing energy. And it will decrease by a quantity W

therefore the following equation is needed;

Figure 3; Equation meaning Heat and Energy = Quality - work

But remember to change the equation!

(This could then become an open system as in figure 1.)

2nd Law;

In a natural thermodynamic process. the sum of entropies of the interacting thermodynamic systems increases.

• Take your no equilibrium system, and carve it up (Mathematically, not physically) into smaller subdomains, each of which has a fairly constant temperature throughout. They don't have to all have the same temperature, they only need to have their own temperature. You treat each subdomain like an "isolated" system, computing all the internal changes in entropy and energy, and then add in any energy and/or entropy that comes across the boundary from any other subdomain that the subdomain in question is in contact with

3rd Law;

The entropy of a system approaches a constant value as the temperature approaches absolute zero. With the exception of non-crystalline solids the entropy of a system at absolute zero is typically close to zero and is equal to the logarithm of the multiplicity of the quantum ground states

References/Further Reading;

Learnengineering.org. (2016). First Law of Thermodynamics for an Open System ~ Learn Engineering. [online] Available at: http://www.learnengineering.org/2013/03/frist-law-of-thermodynamics-open-system.html [Accessed 24 Apr. 2016].

Tim-thompson.com. (2016). Entropy and the 2nd Law in Open Systems. [online] Available at: http://www.tim-thompson.com/entropy3.html [Accessed 26 Apr. 2016].

 

Open and Closed Systems

Open System

The Open Systems Model is based on open systems theory, which perceives organizations as units that interact with their external environment rather than being closed and independent units.

• Inputs processes, outputs goals.
• Healthy open systems continuously exchange feedback with their environments
• Aspect that are critically important to open systems include the boundaries, external environment and equifinality.
• Examples; Rainforest, Tundra's, Everglades

Therefore ALL natural systems are open systems but more then this they exsit as compounds of cascades through which energy and matter flow; the output of one systems forms the input to the next. 

Example; 

Figure 1; shows a comparison of a open and closed system where one is creating an output and input for the environment the other is not.

As Above in Figure 1 shows energy and chemical elements flowing through the biosphere are diverted temporarily  to the biomass store of the organisms of the different tropic levels. Think about the geothermal heat and energy and geochemical elements through the rock-forming materials. How it the crustal system is divided to store the energy and how it links with the open system?  

Closed System

An isolated system (3rd System) that has no interaction with its external environment. Closed systems output are knowable only through their outputs which are not dependent on the system being a closed or open system. Closed systems without any output are knowable only from within.

• Closed Systems have hard boundaries through which little information is exchanged
• Closed system boundaries are often unhealthy
• Example; Earth

Such a model of the planet is obviously simplified. An example would be Meteorites and how they penetrate the earth atmosphere from space, illustrating that of matter also crossing the boundaries of the system.

Figure 2; The Earth as a closed system as it as an input and an minimal output with no mass energy

 Figure 2 shows how earth is a closed system however the water cycle is also a closed system.

More to come on the laws of Thermodynamics and how to relate them open and Closed systems.... 

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References/ Further Reading


Kk.org. (2016). Kevin Kelly -- Chapter 8: Closed Systems. [online] Available at: http://kk.org/mt-files/outofcontrol/ch8-f.html [Accessed 24 Apr. 2016].


White, I., Mottershead, D. and Harrison, S. (1992). Environmental systems. London: Chapman & Hall.