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].