The purpose of a refrigerator is to keep cold (the absense of heat) in a particular place so it can be useful. Under the circumstances it seems wise to explore the mechanisms by which heat moves around so we can better keep it where we want it. I suspect that it may have been the early studies of the movement or transport of heat that lead to the model of heat as a fluid. Certainly fluids show many of the characteristics of heat. You all have had the experience that water always flows downhill just as heat always moves from hot objects to cold objects. Why this should be so is mysterious and may be dealt with later in the quarter. Generally speaking it was found that heat "flows" from object to object in three fairly distinct ways.

The first of these processes occurs when a hot object is placed in physical contact with a cooler object. Imagine an ice cube placed in your hand. The hot object grows cooler (your hand feels cold) and the cool object get warmer (the ice cube melts). This process which depends on direct physical contact between the two objects is known as thermal conduction. We have a lot of personal experience developed over our childhood years of which hot objects are touchable and which are not. Sticks whose far end is burning (like hot!) are OK to pick up but metal bars whose far end is glowing are a riskier proposition. The difference between these two experiences has to do with our awareness that each material conducts heat through itself differently. Metals are pretty good at it and wood is not. This characteristic of materials is described as its thermal conductivity and is quantified by a coefficient of thermal conductivity.

Reading:

Find the section(s) on thermal transport. These will cover:

Thermal Conduction

Start by developing a conceptual understanding of each mechanism. Then find the formula which mathematically describes the mechanism (doesn't exist for convection) and be sure that you understand what each term means.