Practically Science: Heat
When autumn cools outdoor temperatures, we practically hairless humans heat our homes to keep warm and wear extra clothing when we go outside.
What is heat, anyway?
Heat is energy stored inside everything—skateboards, screwdrivers and squash, for example. This energy keeps the atoms and molecules inside the skateboard moving. The measure of the object’s energy level is temperature, and we measure how hot or cold something with a thermometer.
Heat transfers…
If you stick a cold screwdriver into a hot squash, what happens? The screwdriver gets hot. As the squash gives up energy to the screwdriver, the squash temperature falls. The screwdriver’s temperature rises.
Now, apply the idea of heat transfer to a person, temperature 98.6 degrees, going outdoors when the temperature is 40 degrees. Without some way to prevent the heat transfer, the person gives heat to the environment until he cools to air temperature. If the person stays indoors, heat transfer slows but does not stop.
Hat’s on
Cool weather clothing slows the exchange of heat between your body and the air outside. Hats slow the heat transfer by 60%. Coats made of wool fibers or lined with down feathers are the best insulators. Insulators are materials that interfere with the transfer of heat from the body.
Doesn’t this make sense? After all, wool keeps sheep warm in the coldest climates. Down feathers protect penguins that spend their year in the Antarctic.
Heating our homes
Many American homes have central heating —systems that use a fuel such as natural gas or electricity to generate heat. Fans circulate the warm air through ducts or passageways in the house. The hot air returns or vents are sites through which hot air comes into the room. Usually your cat or dog sleeps on these vents.
How does your home know when to turn on or shut off the heat?
Thermostats
Thermostats are fancy switches that turn your central heating system off and on. One type of thermostat uses mercury bulbs and coils of wire to sense the temperature and make the electrical connections that direct the heating system. Warm enough. Turn off the system. Too cool. Okay, turn on the system.
New digital thermostats operate using different methods, but on the same principles.
To find out more, try these links.
What Digital Thermostats Can Do
3M Company Explains How Clothes Insulate
An Instrument Maker Explains Thermometers’ Evolution
