Discover, Manipulate, and Compare Formulas 

Find equations for the Doppler shift in frequency using a natural-language query.

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X FormulaLookup["doppler shift frequency"]

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Get a specific equation.

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X FormulaData[{"DopplerShift", "Frequency"}]

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Define functions that solve for specific quantity variables.

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X doppler[v_] := Last@FormulaData[{"DopplerShift", "Frequency"}, {QuantityVariable[ \!\(\*SubscriptBox[\("f"\), \("s"\)]\),"Frequency"] -> Quantity[400, "Megahertz"], QuantityVariable[ \!\(\*SubscriptBox[\("v"\), \("s"\)]\),"Speed"] -> v, "c" -> Quantity[1, "SpeedOfLight"]}]

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X dopplerrelativistic[v_] := Last@FormulaData[{"DopplerShiftRelativistic", "Frequency"}, {QuantityVariable[ \!\(\*SubscriptBox[\("f"\), \("s"\)]\),"Frequency"] -> Quantity[400, "Megahertz"], QuantityVariable[ \!\(\*SubscriptBox[\("v"\), \("s"\)]\),"Speed"] -> v}]

Compare relativistic and nonrelativistic formulas.

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X Plot[{doppler[Quantity[v, "SpeedOfLight"]], dopplerrelativistic[Quantity[v, "SpeedOfLight"]]}, {v, 0, 0.9}, Frame -> True, FrameLabel -> Automatic]

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