Guided Reading Chapter 7 PDF

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Chapter 7.1: Woodstoves Vocabulary (short definition/use in a sentence) • • • • • • •

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Thermal equilibrium o Possessed by two objects with the same temperature Heat o Thermal energy on the move Chemical reaction o Thermal energy is released by a chemical reaction between molecules Activation energy o The energy needed to initiate the chemical reaction Heat exchanger o A device that transfers heat without transferring the hot molecules themselves Conduction o Occurs when heat flows through a stationary material Thermal conductivity o The measure of how rapidly heat flows through a material when it is exposed to a difference in temperatures Convection o Occurs when a moving fluid transports heat from a hotter object to a colder object Radiation o Unlike conduction and convection, radioactive heat does not depend on atoms/molecules/electrons to carry heat o Occurs in space, when two objects are touching each other Electromagnetic waves o Mechanisms of heat transfer Heat capacity o The amount of heat that must be added to an object to increase its temperature by 1 unit Specific heat o Quantity that measures a material’s heat capacity per unit mass

Units (what quantity is measured in the following) • •

J/(kg K) o Unit of thermal heat W/(m*K) o Unit of thermal conductivity

Equations and physical laws (express in words) •

Specific Heat

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Equal to heat capacity / mass

Example problems/questions: 1. You put your leftovers after dinner into the refrigerator. Which way is heat flowing? Is this a heat exchanger? a. Heat flows naturally from warm objects to cold objects, so in this case the leftovers in the fridge are losing heat. In this case, the heat exchanger in the fridge itself. 2. You make a batch of cookies by placing a sheet tray on the shelf in the middle of your oven. Describe the heat transfer processes by which the cookies bake. a. The cookies are baked by radiation, where the heaters in the oven radiate energy and warm up the cookies. 3. You can use a blender to crush ice cubes, but if you leave it churning too long, the ice will melt. What supplies the energy needed to melt the ice? a. The friction created between the ice cubes and the blender, as well as the mechanical energy generated by the blender, warm up the contents of the blender. In this case, that is why the ice begins to melt....