rate of heat loss Introduction Aim: To investigate the factors which affect how well an object retains heat. My investigation is to find out the rate of which heat transfer happens. Heat transfer is a process in which energy in the form of heat energy is exchanged between materials that are at a different temperature. Heat is generally transferred by conduction, convection, radiation and evaporation. All of these processes can all happen simultaneously but it is likely that one will give the greater heat exchange. Heat is exchanged through the brick wall by conduction. The surfaces of a high-speed aircraft are heated up by convection. The earth is heated by heat that is being radiated from the sun.These experiments involve the temperature of hot water being recorded at chosen intervals in a polystyrene cup.Here is a description of the following processes that will affect my experiment:Conduction This is where heat energy passes through the walls of the can by making the particles of the cup vibrate and then they will make the particles next to them vibrate causing the heat to pass through the walls of the cup and out to the surroundings. Materials that are good thermal conductors tend to be good electrical conductors; metals such as gold, silver and copper have high thermal conductivity's and will conduct heat readily. Materials such as glass have much smaller heat transfer values and are poor heat conductors.ConvectionThis is where the cooler water particles sink down to the bottom and the warmer water particles float up to the top. Convection will only affect my experiment if I don’t use a lid. This is because the warm water will float up to the top and the heat energy will escape out of the top. If a pan of water was being heated from below then the water particles at the bottom of the pan will become warm as therefore become less dense, they will begin to rise to the top of the pan. As the warmer water particles begin to rise, the cooler water particles at the top of the pan will sink to the bottom, as the are less dense. Once at the bottom
