List of Words for Letter ‘R’
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radiant energy
the energy given off by the Sun
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radiation
the transfer of energy by electromagnetic waves
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raw materials
a building block of products
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reactant
an original substance in a chemical reaction
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recycling
the creation of new products by the reuse of materials that would otherwise be treated as waste
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relative humidity
a measurement of the amount of water vapor in the air compared to the amount that would saturate the air
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renewable resource
a resource that can be replaced in a relatively short time; examples are wood, water, wind, and solar energy
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respiration
the process through which energy is released in plants and animals and occurs when sugars and oxygen join to produce water, carbon dioxide, and energy
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Richter scale
a set of numbers used to describe the magnitude of an earthquake
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Ring of Fire
a zone of frequent earthquakes and volcanic eruptions encircling the Pacific Basin
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rock cycle
a continuous cycle in which rocks are continually changed from one type to another
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root
the part of a plant that holds it in the soil and takes in water and minerals to feed the plant
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root pressure
force that moves water upward into the stem and in small plants it can move water through the plant.