Silver Burdett/

Science: Understanding Your Environment/

Producing Heat andLight p. 147/

1975/

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/

S4N13/

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/-/What do you think*- of [ARwhen you hear*D1 the words "heat"=A--01 and "light"?=A--02 ]/-/What ideas come*- (to your mind? )/-/Do you think*- (of the sun? )/-/There is*N1 good reason to think=IAJ050 (of the sun )[ARwhen you hear*D1 these two words. ]/-/Almost all the energy [JMyou use*D0 ]comes*- (from the sun. )/-/The sun's energy travels*- (through space )(to the earth. )/-/It is called*P2 solar energy, or radiant energy. /-/The part [JMyou see*D0 ]is called*P1 light. /-/Heat does not come*- (through space )(to the earth. )/-/Heat can travel*- only (through matter. )/-/There is*N1 not enough matter (in space )(for heat )to travel.=IOP030 /-/Radiant energy changes*- (to heat energy )[ARwhen it is absorbed*P (by matter. )]/-/Why is space not heated*P (by the radiant energy )passing=P--030 (through it? )/-/Why do spacecraft become*A1 very hot (from the radiant energy )(in space? )/-/Have you noticed*D1 [DOthat air can be*A1 very cold (on a sunny, winter day? )]/c/But dark soil, a street, or a building may feel*A1 warm. /-/Sunlight passes*- (through air )(without much )(of it )changing=SOP060 (to heat. )/-/It cannot pass*- (through soil )or (through the material )(in streets and buildings. )/-/Can radiant energy pass*- (through glass and water )(without changing=GOP030 )(to heat? )/-/Do you know*D1 [DOwhat burning is?*N1 ]/-/You have seen*D1 many different materials burn.=IDO040 /-/You have felt*D1 the heat (from fire. )/-/Fire produces*D1 light [JRyou can see.*D0 ]/-/What is needed*P to have=IAV041 a fire? /-/(Of course )you need*D1 something [JRthat will burn.*- ]/-/You also need*D1 oxygen. /-/Air has*D1 enough oxygen to keep=IAV051 most fires burning.=SDO030 !!!!!!!!