What is the Meaning of Vector Magnitude Symbols?

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Discussion Overview

The discussion revolves around the meaning of vector magnitude symbols, specifically the notation |U|, and the role of unit vectors in vector representation and manipulation. Participants explore the implications of these symbols in both theoretical and practical contexts.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question whether the symbols | | represent the absolute value of a vector's size or if they have a distinct meaning, suggesting that |U| implies the magnitude of U.
  • One participant states that |U| (defined as sqrt()) is the magnitude or length of a vector, which is a scalar quantity.
  • There is a suggestion that unit vectors are used to break down vectors into components, although questions arise about how this applies when vectors are given without coordinates.
  • Another participant clarifies that |\vec U| represents the magnitude of the vector \vec U, emphasizing that vectors possess both magnitude and direction.
  • It is noted that every vector \vec U can be expressed as \vec U=|\vec U|\vec e, where |\vec U| is the magnitude and \vec e is the unit vector in the direction of \vec U.
  • A participant mentions that the unit vector in the direction of U can be represented as U/|U|.

Areas of Agreement / Disagreement

Participants generally agree on the interpretation of |U| as the magnitude of the vector, but there are varying levels of understanding regarding the application of unit vectors and their necessity in vector manipulation. The discussion remains somewhat unresolved regarding the use of unit vectors when vectors are presented without coordinates.

Contextual Notes

Some limitations include the dependence on definitions of vector magnitude and unit vectors, as well as the potential ambiguity in applying these concepts without specific coordinate information.

CinderBlockFist
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when you use these symbols | |, does that mean absolute value of the vector size (since it is same as absolute value symbols)? Or do they just have a different meaning, that we just write the same symbols. So |U| automatically implies just the magnitude of U?

Also, what is a unit vector e used for? Why do we need to multiply a vector U by this unit vector? If the problem provides me w/ an arrow and vector U = 50 Newtons. Why do I need to multiply it by e? I don't gett it.
 
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Yes |U| (sqrt(<U,U>)) is the magitude or length of a vector and is therefore a scalar. The unit vectors form basis which allows you to define U in terms of scalars (it's components in that basis).
 
So the unit vector e is used to break up the vector into components? What if the vector U is given only in vector ie. 50 Newtons w/out any coordinates? BTW thanks for the response
 
Yes, [itex]|\vec U|[/itex] is just the magnitude of the vector [itex]\vec U[/itex], it's just a (positive) number. (Remember, vectors have both magnitude and direction).
When you're only interested in the magnitude, you use [itex]|\vec U|[/itex].
In mathematics it's more commonly called the 'length' or the 'norm' of the vector and written [itex]||\vec U||[/itex].

Likewise, when you are not interested in the magnitude but only in the direction of the vector, use the unit vector of [itex]\vec U[/itex]. It's a vector with length 1 and points in the direction of [itex]\vec U[/itex].
Every vector [itex]\vec U[/itex] can be written as [itex]\vec U=|\vec U|\vec e[/itex], where |[itex]\vec U[/itex]| is the magnitude of the vector and [itex]\vec e[/itex] is the unit vector in the direction of [itex]\vec U[/itex].
 
The unit vector in the direction of U is U/|U|.
 
Thanks guys
 

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