Sci 122 Telecourse Program 26 Kinetic Theory

# 1. Introduction

The pool table is one of the best models for visualizing the kinetic theory of gases, with one important imperfection, which is is friction, which causes the balls on the table to slow down.

# 2. Pressure, Volume, Temperature

## 2.1. Pressure

### 2.1.6. pressure in a liquid

 The level to which a liquid rises is the same regardless of the shape of its container. This is because the pressure depends on the depth, and because the pressure is equal in all directions.

# 5. Boyle's Law

## 5.1. demo: squeeze a balloon until it pops

The fact that decreasing volume increases pressure can be shown qualitatively with a balloon. Try it with a balloon of your own.

## 5.6. Boyle's J tube

 The pressure inside of the closed part of the tube is equal to the equivalent of two atmospheres of pressure (one atmosphere from the atmosphere itself and one from the 30-inch column of mercury. The volume of air inside the closed end is twice as large as when the pressure is half as much, or one atmosphere.

## 5.7. demo: Boyle's Law apparatus

The video program shows how the volume and pressure are inversely proportional using a pressure gauge and a glass cylinder with a piston.

# 8. Explanations for the Gas Laws

## 8.1. Boyle (1662): Static vs. Kinetic

Boyle argued that the properties of gases were due to stationary, compressible particles.

# 9. Kinetic Theory of Gases

## 9.6. Postulates of Kinetic Theory

A postulate is an assumption to be tested. In this case it is a model. We assume certain things about the nature of gases, then determine whether or not the behavior of gases is consistent with. We use the Newtonian paradigm (forces, momentum, energy) as a starting point for understanding the gas laws and other properties.

# 12. Summary & Conclusions

In this lesson we have seen how the kinetic theory of matter, originally formulated to explain the gas laws, can be extended to other forms of matter. Many, if not all aspects of the physical behavior of matter can be explained or understood in the context of kinetic theory.

It is through kinetic theory that we obtain our best understanding of the distinction between heat and temperature and the nature of heat as a form of energy.

It also allows us to understand how conduction takes place as energy is transferred molecule to molecule by elastic collisions.