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Thermal Energy Chapter 6 Section 1 Temperature & Heat Part 1 Warm Up: • To shape metal into a horseshoe, the metal is heated in a fire. Why will a horseshoe bend when it’s very hot, but not after it cools? What was different ? • There was • Matter is more motion in always in the hot water motion • Particles of gases, liquids, and solids all • The energy of move motion is Kinetic Energy Heat Heat is related to temperature: The Temperature of an object is the measurement of the average kinetic energy (KE) of particles What do Temperature Scales Measure? • Fahrenheit: used in US • Celsius: used in other countries • Kelvin: SI unit 0 K = -273°C 0°C = 273 K Thermal Energy • Thermal Energy (Q) is the sum of the kinetic energy + the potential energy of all the particles in an object: Q = KE + PE Thermodynamics • First Law of –Energy is Thermodynamics: CONSERVED the increase in thermal energy of a system equals the work done on the system plus the heat transferred to the system Open Systems • In an open system, heat flows across the boundary, or work is done across the boundary. • What are examples of open systems? Closed Systems • In a closed system, no heat flows across the boundary and no work is done across the boundary. • What are examples of closed systems? Thermodynamics • Second Law of Thermodynamics: Heat flows from warmer objects to cooler objects Heat cannot flow from a cooler object to a warmer object unless work is done How do solids transfer heat? • Conduction: the transfer of thermal energy by collisions between particles in matter. • Particles in solids vibrate and collide with each other • List 3 examples of conduction Convection • Convection is the transfer of thermal energy in a gas or liquid by the movement of warmer and cooler fluid from place to place. Knowing this, what will happen to a piece of ice floating at the top of a warm glass of water? What will happen to a piece of ice at the bottom of a glass of water? • List 3 examples of convection Radiation • Radiation is the transfer of energy by electromagnetic waves. These waves travel in the empty spaces between particles until their energy is absorbed by a particle. • Would radiation pass • List 3 examples through a solid or a gas of heat radiation. more easily?
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