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Can the magnitude of vector be negative? 
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#1
Sep1809, 09:14 PM

P: 492

Recently I was told that scalars, although magnitude only, can be negative. Does this mean that the magnitude of a vector can be negative too?
Also, I'm wondering if there's a difference between the absolute value and magnitude of a vector like 3i4j. Thanks for any help that you can provide 


#2
Sep1809, 09:29 PM

P: 218

no, the magnitude of a vector is computed by sqrt(x1^2 + ...... xn^2)



#3
Sep1809, 09:43 PM

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#4
Sep1809, 09:49 PM

P: 218

Can the magnitude of vector be negative?
the absolute value of a vector is the "norm"



#5
Sep1909, 07:14 AM

Sci Advisor
PF Gold
P: 1,843

The magnitude (a.k.a. norm or length) ǁaǁ of a vector a is a scalar and is always positive (or zero).
But there are scalars that are not magnitudes of vectors and they can be negative. (For example the scalar product (a.k.a. dot product or inner product) of two vectors a.b). 


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