HEAT TRANSFER Science 7 Quarter 3 PDF

Science 7 Quarter 3 HEAT TRANSFER RECALL: Chat H if the statement define Heat and T for Temperature 1. The transfer of thermal energy from one object to another. H 2. The measure of hotness or coldness of an object. T 3. It is the “energy in transit.” H 4. It is m...

Science 7 Quarter 3 HEAT TRANSFER RECALL: Chat H if the statement define Heat and T for Temperature 1. The transfer of thermal energy from one object to another. H 2. The measure of hotness or coldness of an object. T 3. It is the “energy in transit.” H 4. It is measured in degrees Celsius or degrees Fahrenheit or Kelvin. T  In Heat Transfer… Heat always moves from a warmer place to a cooler place. Hot objects in a cooler room will cool to room temperature. Cold objects in a warmer room will heat up to room temperature.  If a cup of coffee and a red pop sickle were left on the table in this room what would happen to them? Why?  The cup of coffee will cool until it reaches room temperature. The pop sickle will melt and then the liquid will warm to room temperature. 1 2 3 Conduction A process by which heat is transmitted through a material from one particle to another and occurs when there is direct contact. Conduction When you heat a metal strip at one end, the heat travels to the other end. As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this? Conduction Metals are different The outer e______ lectrons of metal atoms drift, and are free to move. When the metal is heated, this ‘sea of inetic electrons’ gain k_____ energy and transfer it throughout the metal. Insulators, such as w___ ood and p____, lastic do not have this ‘sea of electrons’ which is why they do not conduct heat as well as metals. Why does metal feel colder than wood, if they are both at the same temperature? Metal is a conductor, wood is an insulator. Metal conducts the heat away from your hands. Wood does not conduct the heat away from your hands as well as the metal, so the wood feels warmer than the metal. Convection A process by which heat is transferred or transmitted from one place to another by the movement of heated particles of a liquid or gas. Convection What happens to the particles in a liquid or a gas when you heat them? The particles spread out and become less dense. A liquid or gas. This effects fluid movement. What is a fluid? Fluid movement Cooler, more d____, ense fluids sink through w_____, armer less dense fluids. In effect, warmer liquids and gases r___ ise up. Cooler liquids and gases s___. ink Why is it windy at the seaside? Cold air sinks Where is the Freezer freezer compartment compartment put in a fridge? It is warmer at the It is put at the bottom, so top, because this warmer cool air sinks, air rises and so it cools the a convection food on the current is way down. set up.  Radiation A process of transmitting energy in the form of electromagnetic waves. How does heat energy get from the Sun to the Earth? There are no particles between the Sun and the Earth so it CANNOT travel by conduction or by convection. RADIATION ? earthwithtilt  Technologies in Transforming Heat into Electrical Energy Thermomagnetic generators Convert waste heat into electricity Thermal Photovoltaic Cells Antora Energy has created special cells much better than regular solar cells, producing 100 times more power in similarity sized devices. These cells efficiently convert high temperature heat into electricity. Radiation Radiation travels in straight lines True/False Radiation can travel through a vacuum True/False Radiation requires particles to travel True/False Radiation travels at the speed of light True/False  Identify the heat transfer illustrates in the following picture. Chat CONDUCTION, CONVECTION and RADIATION. Radiation Conduction Convection