575_Physics ProblemsTechnical Physics

575_Physics ProblemsTechnical Physics - Chapter 20 577...

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Chapter 20 577 Q20.20 At night, the Styrofoam beads would decrease the overall thermal conductivity of the windows, and thus decrease the amount of heat conducted from inside to outside. The air pockets in the Styrofoam are an efficient insulator. During the winter day, the influx of sunlight coming through the window warms the living space. An interesting aside—the majority of the energy that goes into warming a home from sunlight through a window is not the infrared light given off by the sun. Glass is a relatively good insulator of infrared. If not, the window on your cooking oven might as well be just an open hole! Glass is opaque to a large portion of the ultraviolet range. The glass molecules absorb ultraviolet light from the sun and re-emit the energy in the infrared region. It is this re-emitted infrared radiation that contributes to warming your home, along with visible light. Q20.21 In winter the produce is protected from freezing. The heat capacity of the earth is so high that soil freezes only to a depth of a few decimeters in temperate regions. Throughout the year the
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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