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#1 2013-08-16 06:59:46

atran
Member
Registered: 2013-07-12
Posts: 91

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...

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#2 2013-08-16 07:23:30

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,753

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 agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#3 2013-08-16 07:29:24

atran
Member
Registered: 2013-07-12
Posts: 91

Re: Quantity, Magnitude, Unit

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

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#4 2013-08-16 07:55:24

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,753

Re: Quantity, Magnitude, Unit

The magnitude is 10 meters.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#5 2013-08-19 00:53:17

atran
Member
Registered: 2013-07-12
Posts: 91

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?

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#6 2013-08-19 01:24:15

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,753

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 agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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