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CH 14 TEMPERATURE, HEAT, AND EXPANSION

CH 14 TEMPERATURE, HEAT, AND EXPANSION. Temp. = average KE of mlcs. K= o C + 273. Heat = transfer of energy because of a temp. difference. Heat flows from a hot thing to a cold thing. Internal energy = sum of all KE in an object. Specific Heat Capacity p260.

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CH 14 TEMPERATURE, HEAT, AND EXPANSION

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  1. CH 14 TEMPERATURE, HEAT, AND EXPANSION Temp. = average KE of mlcs. K=oC + 273 Heat= transfer of energy because of a temp. difference. Heat flows from a hot thing to a cold thing. Internal energy= sum of all KE in an object.

  2. Specific Heat Capacity p260 The specific heat capacity of any substance is defined as the quantity of heat required to change the temperature of a unit mass of the substance by 1 degree Celsius. Dirt has a low Specific Heat. 1 cal of heat will raise 1g of it several oC Here’s a thought… Its how much heat a material can absorb or give off without a big temp. change. Water has a high SpHt. 1 cal of heat will raise 1g of it only 1oC

  3. More Specific Heat Mouth is in for a big surprise. Why? Fingers on crust don’t feel hot. Why? The watery insides of the pie has a high spht. It holds a lot of internal energy. Crust has low spht. What little internal energy is in it transfers quickly and painlessly as heat. All that internal energy transfers quickly and painfully as heat. Think of the aluminum foil around a baked potato. Think of a fire hose. Think squirt gun.

  4. One more idea from ch. 14: p266 Smile means big fish has had lunch. Air temp. Ice is not as dense as water so it floats. How do the densities of 0oC and 4oC water compare? 4oC water is as dense as water gets. 0oC water is less dense. 5oC water is less dense.

  5. Chap. 15 Heat Transfer p270 An object at a higher temp. transfers some of its energy to an object at a lower temp. The energy being transferred is called HEAT. Wood and tile are the same temp. Why does wood floor feel warmer? Why does tile feel colder? Tile is a better conductor and heat flows more quickly. Wood is an insulator. The transfer of heat is slow.

  6. 1. Conduction: heat flow with contact. The feet… Grass is a poor conductor Very little heat is transferred to snow so it doesn’t melt. A portion of the roof is a good conductor. So, snow melts.

  7. 2. Convection: heat transferred through motion of fluid. Land, lower spht, same amount of heat warms it up faster than the water. Land cools faster bec. The loss of a little heat means that it cools more. Heat sources. Why does land warm up more and cool off more?

  8. 3. Radiation p275 The Greenhouse Effect and Global Warming p280 CO2 absorbs heat radiated from the ground (long waves) but lets visible light through (short waves).

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