Thermodynamics

Why do we need to know this stuff?

sidingThermodynamics is one of the most critical things for human survival. We can actually survive longer without air than we can withstand very extreme cold or heat. But even with more normal temperature exposure from the weather familiar to us, most of us could not survive the year without some sort of protection from the temperature changes.

What is the big picture?

After air and water, many people will see the most basic needs as “food, clothing, and shelter”. Food, air, and water meet our body’s chemical needs. Clothing and shelter meet our body’s thermodynamic needs. In simple language, we need energy and we need to stay warm.  Our body uses the food we eat to create the heat we need to make everything function as it should and we feel comfortable.  But, in most places in the world, we need shelter to help us stay warm or cool when temperatures vary.

Where is thermodynamics in your life?

There are three big ideas in this unit: Radiation, Conduction, and Convection.  As you work through the material in this unit, you learn how thermodynamics works in your everyday life.  This knowledge will make you more comfortable and save you money.

RADIATION

Heat and light are two forms of radiation that we experience every day.  Radiation travels through empty space.  Space without air is a vacuum.  The light from the sun travels through the vacuum of space to get to Earth.  This light from the sun comes in through the windows of your house and is absorbed by furniture, walls, and floors and is reradiated as heat.  This can feel good in the winter but may make your house or a room too warm in the summer.  Understanding radiant energy like heat and light becomes important for learning how to make your home more comfortable and also save money on heating and cooling bills.

CONDUCTION

windowsHeat travels along a metal handle by means of conduction.  When you place a metal skillet on the heating element of a range, the handle gets hot even though the heating element is under the skillet and not on the handle.  The vibrations of atoms or molecules in solids, liquids, or gases is what we call heat.  Heat travels through the skillet to the handle by neighboring molecules vibrating other molecules and spreading out to the handle.  The more heat there is in a material the faster the particles are moving.  All materials conduct heat, even wood.  Understanding conduction can help you slow down heat loss from your home and save you money and also keep you more comfortable.

CONVECTION

Moving air is generally thought of as convection.  When you open a hot oven, hot air rises into your face.  Rising hot air is called convection.  When you open a refrigerator in you bare feet, you can feel the cold air falling against your skin.  This falling cold air is called convection.  Even with no wind outside in the winter, when you open the door to your house, warm air will move out the door and rise through the cold air outside.  As this warm air leaves your house, cold air from outside moves in to take its place.  Understanding convection can help you slow down heat loss from your house in the winter or air-conditioned air loss in the summer.  Knowing how convection works will help you keep your home more comfortable and save you money.

Where is thermodynamics in your life?

After air and water, many people will see the most basic needs as “food, clothing, and shelter”. Food, air, and water meet our body’s chemical needs. Clothing and shelter meet our body’s thermodynamic needs. In simple language, we need energy and we need to stay warm. Our body uses the food we eat to create the heat we need to make everything function as it should and we feel comfortable. But, in most places in the world, we need shelter to help us stay warm or cool when temperatures vary.