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Unit 6. Temperature Temperature – A measure of the average kinetic energy of the particles in an object (how hot or cold). There are three common temperature.

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Presentation on theme: "Unit 6. Temperature Temperature – A measure of the average kinetic energy of the particles in an object (how hot or cold). There are three common temperature."— Presentation transcript:

1 Unit 6

2 Temperature Temperature – A measure of the average kinetic energy of the particles in an object (how hot or cold). There are three common temperature scales: Fahrenheit (water freezes at 32° and boils at 212°). Celsius (water freezes at 0° and boils at 100°). Kelvin (water freezes at 273° and boils at 373°). Thermometer – A device used to measure temperature. Thermal Equilibrium – When no energy flows from one object to another that are in contact with each other.

3 Kinetic Theory The Kinetic Molecular Theory of Matter is a concept that basically states that: ATOMS and MOLECULES possess an energy of motion (kinetic energy) that we perceive as temperature.

4 Kinetic Theory In other words ATOMS and MOLECULES are constantly in motion and we measure the energy of these movements as the temperature of that substance.

5 Kinetic Theory This means if there is an increase in temperature the atoms and molecules will gain more energy (kinetic energy) and move even faster.

6 Heat Transfer Heat – The energy that is transferred from one body to another because of a difference in temperature. Heat is not a property of an object. Example: The iron is hot, so it's reasonable to say it must have a lot of heat in it. Reasonable, but wrong. It's more appropriate to say that it has a lot of energy in it (i.e. it has a high temperature), and touching it will cause that energy to transfer to your hand... in the form of heat.

7 Heat Transfer Heat continued: Heat always flows from high temperature to low temperature. The SI unit of heat is the joule ( J ). Types of Heat Transfer: Conduction – Energy transfer from particle to particle within a substance, or from one material to another when the two are in direct contact. Requires a medium. Example: A spoon left in a pan of soup on the stove.

8 Heat Transfer (cont.) Convection – A means of heat transfer by movement of the heated substance itself, such as currents in a fluid. Requires a medium. Example: Air near the surface of the Earth being heated by the Sun and rising in the atmosphere. Radiation – Energy transmitted by electromagnetic waves. Does not require a medium. Example: The heat you feel when you stand in front of a fireplace. Conductor – A material through which heat can be transferred easily. Insulator – A material through which heat is not transferred easily.

9 The Laws of Thermodynamics Thermodynamics – The study of processes in which energy is transferred as heat and as work. The Zeroth Law of Thermodynamics - If body A is in thermal equilibrium with body B and body B is in thermal equilibrium with body C, then body A is in thermal equilibrium with body C. The First Law of Thermodynamics – The law of conservation of energy. A change in the internal energy of a system is equal to the sum of the heat added to the system and the work done on it.

10 The Laws of Thermodynamics The Second Law of Thermodynamics – Heat cannot be transferred from a colder to a hotter body within a system. Entropy – (Physics definitions) The quantitative measure of disorder in a system. a measure of the amount of energy which is unavailable to do work.


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