Thermodynamics

Thermodynamics Lab (Division C) and Keep the Heat (Division B) are slated as national events in the 2011-2012 season. Keep the Heat was formerly run as a trial event in Minnesota, replacing Egg-O-Naut because Minnesota winters are too cold to run outdoor events involving liquid water.

Overview
In this event you create a model or device that simply insulates a 250ml Pyrex beaker filled with 100ml of hot water. Your goal is to create a device that loses the least amount of heat after a period of time determined by the instructor (20-30 minutes). While your device is being tested you take a short test on heat (conversions, specific heat, etc). The starting temperature can be anything from 50 degrees Celsius to 90 degrees Celsius (determined by the instructor). Participants will also need to estimate the amount of heat lost according to graphs made prior to the competition (see "Construction").

Device
The Thermo Lab device must fit inside a 30cm cube. If it does not fit, the device will be disqualified. The beaker must be a 250ml Pyrex beaker and it must be easily removable. There should also be easy access to the interior of the device for temperature measurement by the instructor. Plugs are allowed as well as covered loose fiberglass.

Construction
Prior to the competition, competitors should make cooling curve graphs for various starting temperatures so they can easily identify the final temperature at the competition.

Test
The Thermo Lab test can have many different things on it. A Thermo Lab test may include (but is not limited to): temperature conversions, definitions of heat units, heat capacity, and specific heat calculations. No notes or resources may be used on this test. You are allowed a nonprogrammable-nongraphing calculator.

Basic Thermodynamics
Thermodynamics is the study of thermal energy along with how it interacts with matter and energy (Another definition is Lord Kelvin's, and that is: "Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency.")

The Four Laws of Thermodynamics
There are four basic laws of thermodynamics that apply to any situation that meets the requirements of the specific law (Although the laws are actually start with the zeroth law and end with the third since the zeroth law was created later).

Zeroth Law of Thermodynamics: If two objects have the same temperature as a third object, the two objects have the same temperature.


 * This law is rather self explanatory, but it can be represented in math as: if $$a=c$$ and $$b=c$$, $$a=b$$.

First law of thermodynamics: Any change in the internal energy of a closed system is equal to the difference between the intake of heat the system receives and the work that the system does.


 * This basically means that if a closed system receives more net heat than net work that it does, it would gain internal energy, and if the net work exceeds net heat intake, the closed system would lose energy (This can be represented in mathematics where i=change in internal energy, h=net heat intake, and w=net work as: $$i=h-w$$, and that means that when $$h>w$$, $$i>0$$. In addition, $$i<0$$ when $$h<w$$, and $$i=0$$ when $$h=w$$.) One factor that supports this law is the Law of conservation of Energy.

Second Law of Thermodynamics: Heat can't instantly go from a colder location to a warmer one.


 * This law explains entropy in that as the temperature of one object nears the temperature of another object, the amount of entropy increases increases, and this entropy must be decreased in order for work to be done. One example for this is a steam engine. As a steam engine is used, the metal and water in the steam engine will retain heat until the temperature of the metal and water is equivalent to the temperature of the fire that they are above. This waste heat can be removed by either the usage of cooling water or shutting the steam engine down until it cools down to a fair temperature.

Third Law of Thermodynamics: As a system's temperature nears absolute zero, all processes stop and the entropy approaches a minimum value.


 * The importance of this law is that it proves that it is impossible for an object reach absolute zero. The reason for this is that as an object reaches lower temperatures, the molecular/atomic process slow which decreases heat transfer while the amount of work done (In this case it is molecular in the form of heat transfer.) decreases in an asymptotic approach and exponential decay due to the First and Second Laws of Thermodynamics. One example of this is that if there was an object at absolute zero touching another object that is significantly warmer, the warmer object would lose temperature in ever decreasing amounts as there is less energy for the warmer object to give to the colder object (The colder object also gains energy due to the Law of Conservation of Energy and would have less of a potential to receive energy.). That allows both of the objects' temperatures to be tracked using an exponential decay graph for the warmer object and a graph of exponential growth for the colder object (with temperature as the y axis and time as the x axis), and both graphs would have an asymptotic approach toward a certain temperature value (This situation is like constantly dividing 1,000,000 in half in an attempt to reach zero.). That means that an object can never be at absolute zero unless an object can be at a temperature lower than that.

Vocabulary
Internal energy: The energy of the motions of atoms and molecules within an object (includes potential energy of molecules and atoms in liquids and solids). Temperature is the measure of the internal energy of an object.

Entropy (when applied to thermodynamics): The amount heat that can't be used to do work.

Absolute Zero: The temperature at which all processes stop (defined in the third law of thermodynamics). This temperature is: 0 degrees Kelvin, -273.15 degrees Celsius, or -459.67 degrees Fahrenheit.

Links
http://www.minnesotaso.org/Files/KEEP%20THE%20HEAT.pdf

Wikipedia-Thermodynamics

Hyperphysics-Thermodynamics