Quick dot product question

  • Thread starter don_anon25
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  • #1
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What is the dot product of a unit vector (e) with a non-unit vector (A)? Is this some sort of identity?

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don_anon25
 

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  • #2
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don_anon25 said:
What is the dot product of a unit vector (e) with a non-unit vector (A)? Is this some sort of identity?

Thanks,
don_anon25

Let a be a unit vector and b be another vector. a * b = |a||b|cosθ. Since a is a unit vector, this becomes a * b = |b|cosθ. I believe that without more information, this is as far as it can be simplified.
 
  • #3
robphy
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don_anon25 said:
What is the dot product of a unit vector (e) with a non-unit vector (A)? Is this some sort of identity?

Thanks,
don_anon25

[tex]
\hat e\cdot\vec A[/tex] is the component of [tex]\vec A[/tex] along the [tex]\hat e [/tex]-direction.
 

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