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## #1 2013-08-17 04:59:46

atran
Full Member

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### Quantity, Magnitude, Unit

Hi,

There are at least two types of quantity: scalar quantity and vector quantity. Both have magnitude, but only the vector quantity has direction. A unit is a magnitude. Thus, if F is a vector quantity, then |F| is the magnitude of the quantity.

Am I thinking right?
Thanks for help...

## #2 2013-08-17 05:23:30

bobbym

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### Re: Quantity, Magnitude, Unit

|F| is the norm or Euclidean distance from the origin of the vector F,

Sometimes it is written like this.

There are other types of norms.

What is A unit?

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #3 2013-08-17 05:29:24

atran
Full Member

Online

### Re: Quantity, Magnitude, Unit

Say x=10 metres: is the magnitude of x 10 or 10 metres? I believe the latter is true.

## #4 2013-08-17 05:55:24

bobbym

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### Re: Quantity, Magnitude, Unit

The magnitude is 10 meters.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #5 2013-08-19 22:53:17

atran
Full Member

Online

### Re: Quantity, Magnitude, Unit

Hi;

The magnitude of a number is its absolute value.
The magnitude of a vector is its length.
The magnitude of a scalar (e.g -10°) is the quantity itself.

Am I thinking right?

## #6 2013-08-19 23:24:15

bobbym

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### Re: Quantity, Magnitude, Unit

Magnitude is always a positive. A scalar is any number. It can be positive or negative.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.