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The World Around
Thinking About Things
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acid amount appears atmosphere atoms attraction become begin bonds called carbon cause centimeter charge chemical cloud considered contains continue crust crystal density direction distance earth effect electric electrons elements energy equal equation example exist experiment fact field Figure force galaxies given gravitational happens heat hydrogen increase kilometers kind known less light look magnetic mass material matter means measure metal meters million molecules momentum motion moving nature negative nucleus object observer occur ocean orbit oxygen particles photons physical planets position possible pressure produced pull push reaction region relative represents result rocks shows side solar solid space speed stars structure surface temperature theory things tion unit universe volume wavelength waves weight