90 Get Warm, Stay Warm!-Mid

Get Warm, Stay Warm! FOCUS Question How can we control heat energy to get warm and stay warm during cold weather?

Brrr! Have you ever taken your temperature? It was probably around 37 degrees Celsius (98.6°F). This is the temperature at which your organs, muscles, and cells are healthiest and most active. The temperature outside is usually much lower than 37°C. Your body keeps warm by making its own heat using energy from food. When it's warm outside, this body heat is enough to keep you warm. But when the outside temperature drops, you need other ways to get warm and stay warm. You can do this by controlling heat energy. Do You Know? Heat is a form of energy. All objects are made of tiny particles that are too small to see. The vibration or motion of the particles is heat. In a cold object, the particles move slowly. As you heat the object its particles move more quickly.

How Heat Moves You can stay warm by keeping heat near your body. Heat moves in three different ways: Conduction occurs when heat moves from one object directly to another. If you leave a spoon in a cup of hot cocoa. the hot liquid makes the handle of the spoon get hot. Convection occurs when liquids or gases move around. carrying heat with them. The movement of the hot air or liquid heats the space around it. Radiation occurs when energy travels in waves. It does not need to pass through any material. You can use all three ways to move heat and keep yourself warm.

A Warm Home Have you ever sat by a fire? It can be very cozy For thousands of years, fire was the only way to heat a home. People around the world still rely upon fire to generate heat. Fire heats a room through radiation and convection. The heat you feel directly from the fire is radiation. Fire also heats the air around it. The air near the fire becomes warm, rises, and is replaced with cool air. The movement of warm air through the room is due to convection. In this wood-burning stove the thick metal warms up through conduction and stores heat. The hot stove releases heat for hours after the fire is out due to convection.

Today most homes use a furnace to keep warm. Furnaces make heat in many ways. Some burn liquid fuel, such as oil or gas. Some burn wood or coal. Others use electricity. A furnace uses convection to move heat through an entire building. Some furnaces use a fan to blow hot air into each room. Others pump hot water or steam from room to room through pipes. The hot pipes warm the air, and the heat spreads due to convection. Technology A space heater warms just one room. It passes electricity through special minerals, which heat up. Some of these devices have a fan to spread the heat throughout a room.

A Warm Body Sooner or later, you have to leave your warm home. You can control heat energy in many ways to help keep your body warm. Exercise can increase your body's temperature from the inside. Warm food and drinks can also help keep you toasty. On very cold days, you lose heat faster than your body can make it. To keep your body warm, you can insulate it, or keep the warmth from escaping. Clothing traps heat inside your body. It holds layers of warm air close to your skin. Thick fluffy materials such as fleece and wool trap more warm air than thin materials such as cotton.