Experimental Approach to High School Physics

with an Emphasis on the Scientific Method

8 Thermodynamics II

In this section of the course, we come back to thermodynamics and work through the concept of an ideal gas. Then we introduce energy and entropy in a major extension to energy concepts. Finally, we abandon our experimental methods and introduce the three laws of thermodynamics.

8.1 Hot Air Balloon—Density, Temperature/Volume Part 1

Density, temperature, volume, scientific method. We invoke buoyancy to explain how the balloon rises. They we try to relate air mass to air temperature

8.2 Liquid Nitrogen and Balloon—Density, Temperature/Volume Part 2

Density, temperature, volume, scientific method, errors. By cooling a small balloon, we see that temperature is related to volume when the mass of air is kept constant.

8.3 Trapped Air, Open Container in the Pool—Density, Pressure/Volume

Pressure, volume, graphing, scientific method, errors. In this session, the students see that the volume of a fixed mass of gas gets smaller as the pressure increases.

8.4 Trapped Air, Closed Container Heated and Cooled—Temperature/Pressure, Absolute Zero

Temperature, pressure, graphing, scientific method, errors. The students discover that the pressure of a contained volume of gas goes up as the temperature increases and down as the temperature decreases.

8.5 Putting it All Together—Ideal Gas Law

Extending a hypothesis, mathematics, graphing, errors, the role of an ideal gas in physics. We use only mathematics to combine the results of the past several class sessions to construct an expression that explains all the observations.

8.6 Ideal Gas Used as Thermometer—Definition of Temperature

Creating a temperature standard, graphing, errors. Here we discover that we have been cheating all along. The temperature was always defined so that the volume of gas at constant pressure is proportional to the temperature.

8.7 Heating and Cooling to Expand Long Metal Rods—Temperature Proxies

Alternate thermometers and their relationship to a primary standard. Definitions, standards, mathematics. We show that at least one other physical phenomena can be reasonably used to define temperature.