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Vector Projection Problem

  • Thread starter Lancelot59
  • Start date
  • #1
634
1
Prob._2112.jpg


I need to find the components of the force along AB along AC.

So I got unit vectors for each like so:

[tex]\vec{AB}=<-1.5,-3,1>[/tex]
[tex]\vec{AC}=<-1.5,-3,3>[/tex]

Norm AB=sqrt(12.25). Norm AC=sqrt(20.25).

Then after multiplying the unit vector AB by the force I tried using the vector projection formula:

[tex]proj_{\vec{AB}}{\vec{AC}}=\frac{\vec{AB}\cdot\vec{AC}}{\norm{AB}\norm{AC}} \vec{AC}[/tex]

But my answer was wrong. I don't know what the right answer is.
 

Answers and Replies

  • #2
gneill
Mentor
20,780
2,759
Verify the components of your vectors, paying attention to the directions of the axes.
 
  • #3
634
1
I see, I had a - in the x component of AC. That did it, thanks.
 

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