Fill in Notes on Heat and Heat Transfer “taking the heat and moving along”
Section I – Heat and Heat Transfer Heat is not matter. It is energy that can changed into other forms and can be transferred by three different methods: Conduction, Convection and Radiation. The movement of heat form a warmer object to a cooler one is called heat transfer.
Section II - Convection: The transfer of heat by the motion of a fluid in the form of currents is called convection. Warm air currents from a heating vent will rise and transfer heat throughout a room. Sinking cold air currents in a cold front will take heat energy away from the warmer surroundings on the ground. The sinking and rising of cold and warm air currents produces wind and brings in and moves out weather patterns
In a deep swimming pool or lake we notice that the colder water is the deeper water. The colder water sinks and the warmer water rises in convection currents that transfer heat in the water. Examples of heat transfer by convection include air conditioning, forced air heating in homes and cars, wind and the mixing of hot and cold liquids together in a tub.
Section III – Conduction: The transfer of heat by direct contact of molecules is called conduction. When fast moving molecules collide with slow moving molecules, the slow moving molecules begin to move faster and collide with other slower moving molecules causing them to move faster. In this way, heat energy is being transferred from molecule to molecule throughout the substance.
Conduction can take place in solids, liquids and gases. Since the molecules are closest together in a solid, heat transfer occurs best between solids. Substances that transfer heat well are called conductors. Metals are very good conductors of heat while wood is a poor conductor, which is known as an insulator. Iron, silver, copper and aluminum are all good conductors and glass, wood, air and plastic are good insulators. Most conductors of electricity are also good conductors of heat as well.
Examples of heat transfer by conduction include the spoon in a hot bowl of soup getting hot, a iron skillet handle getting hot as you cook eggs and getting warmed up as you jump into a warm pool.
Section IV – Radiation: The transfer of heat by electromagnetic waves is called radiation. Electromagnetic waves can travel through empty space and at the speed of light (3.00 x 108 m/s). The sun sends its heat to us from 93 million miles away and takes 8 minutes to reach us. Examples of radiant heat transfer include heat from a fireplace, a candle flame, a hot stove, an electric heater and the sun.