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Types of Energy -kinetic, potential, chemical and thermal -Law of conservation of energy What is Energy? It is the ability to do work or produce heat Exists in two forms ◦ Potential Energy – stored energy ◦ Kinetic Energy – energy of motion Heat is Not the Same Thing As Temperature! What is Temperature? A measure of the average kinetic energy of the particles in a sample of matter. Thermal Energy (Heat) is a Type of Kinetic Energy The energy formed when heat is flowing from a warmer object to a cooler object is called thermal energy ◦ The faster the particles move, the warmer the matter can get ◦ Often represented by a Q for heat ◦ Q can be positive or negative depending on whether an object is getting warmer or colder ◦ Example: matches Chemical Energy is a Type of Potential Energy Energy that is stored in a substance because of its composition is called chemical energy ◦ Energy is stored in the bonds between atoms ◦ Examples: when plants take in radiant energy from sunlight and store it as starches and sugars Law of Conservation of Energy Obeys the Law of Conservation of Energy ◦ In any chemical reaction or physical process, energy can be converted from one form to another, but it is neither created nor destroyed Called First Law of Thermodynamics How do we measure energy and use conversion factors? Units ◦ calorie (cal) – the amount of energy required to raise the temperature of one gram of pure water by one degree Celsius ◦ Calorie (Cal) – is known as a food calorie or a nutritional calorie. 1 Cal = 1000 cal ◦ Joule (J) – SI unit of energy and heat 1 J = 0.2390 cal 1 cal = 4.184 J Example: 1 tablespoon of butter contains approximately 100 Calories. If we burn the butter to produce CO2 and H2O then 100 Cal (100,000 cal) of heat would be released. Practice How many J are in 100 cal? How many Calories are in 65,000 J? 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. There are 3 types of Heat Transfer Conduction – the transfer of energy through direct contact. Conduction requires touching. Example: A spoon in a pot of hot soup becomes warmer because the heat from the soup is transferred to the spoon. Convection – the transfer of heat by the actual movement of the warmed matter. •Heat energy is transferred in a gas or liquid by movement of currents. Convection currents. Does not occur in solids Radiation The heat that you can feel coming off an object. ◦ Heat is radiated from the sun ◦ Heat radiates from a hot object and you can feel that heat without touching it. With an infrared camera, you can see how heat radiates off this elephant. Heat Transfer How does heat behave? How is energy transferred? There are 3 ways that thermal (heat) energy is transferred: 1. Conduction 2. Convection 3. Radiation