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This question is about terminology for physical quantities.

When we talk about magnitude (while talking about scalars and vectors) do we refer to just number or Number along with units?

example: If a person weighs 120 pounds, then "120" is the numerical value and "pound" is the unit.

Which is magnitude? 120? or 120 pounds?


In the book I'm using its written as

The number indicates the magnitude of the scalar quantity and is inversely proportional to the unit chosen.

This statement is wrong. Right? Its not the number alone. Its along with units.

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Don't get hung up on definitions. It really doesn't matter--- you know what the author means--- your weight in kilos is half your weight in pounds. – Ron Maimon Aug 2 '12 at 1:04
up vote 2 down vote accepted

You dont give magnitude of pounds, you give magnitude of , say mass (as here). So the magnitude is 120 pounds.

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After a bit of thinking I myself found the answer.

Let us consider example:

mass of an ant is 1000 milli grams. mass of an elephant is 1 ton.

If just number was taken as magnitude then magnitude of mass of ant would be greater than that of elephant. Which clearly shouldn't be.

So magnitude is number along with units.

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