Saturday, January 29, 2011

Gas Gas Gas

What is a gas? How do gases behave?

This pdf file (link) has great summary of the basics. While in Big Sky you should read sections 13.1 Gases and their Properties and 13.2 Ideal gas calculations. Make sure to read the sections on internal combustion engine and respirations (breathing). These are two great real world examples that illustrate how gases behave. I will provide some links about these topics.

Check out this calculator http://www.altitude.org/air_pressure.php to see how air pressure changes with altitude. Government Camp is at about ~3900 ft, the lodge at Big Sky is ~6800 ft and the summit (lone peak) at Big sky is 11,166 ft, almost as high as the summit of Mt Hood 11,235 ft. Remember that these calculations are approximate as local air pressure is not only dependent on altitude but temperature and humidity which varies (the weather).


Also check out the basics of the internal combustion engine. This is a great example that we can apply the gas laws to. http://www.howstuffworks.com/engine1.htm. Watch the video on this page. The idealized representation of a piston engine is called the Otto Cycle. Click through this diagram step by step and pay careful attention to the pressure and volume changes that occur during the phases of the Otto cycle. This is an idealized representation of what happens in your family car (unless you have a diesel engine). Look at the x and y axis. The x axis is volume and the y axis is pressure. Take note of the changes. A new term to keep in mind is adiabatic, which describes steps of the process that do not transfer heat.

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