1. May 13, 2008 #1

   gtfitzpatrick

   

   1. The problem statement, all variables and given/known data
   
   r.k where r=xi+yj+zk
   
   
   
   3. The attempt at a solution
   
   is the answer to this just z or is it x+y

    

   gtfitzpatrick, May 13, 2008
2. 
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3. May 13, 2008 #2

   cristo

   

   Staff Emeritus

   Science Advisor

   Well, why do you think it is either of the answers you quote?
   
   What is the definition of the dot product of two vectors?

    

   cristo, May 13, 2008
4. May 13, 2008 #3

   gtfitzpatrick

   

   Dot product of 2 vectors a.b is a1b1+a2b2+a3c3?

    

   gtfitzpatrick, May 13, 2008
5. May 13, 2008 #4

   gtfitzpatrick

   

   i think k.k = 0

    

   gtfitzpatrick, May 13, 2008
6. May 13, 2008 #5

   cristo

   

   Staff Emeritus

   Science Advisor

   Ok, good. So, presumably, this definition is for two vectors a=(a1,a2,a3) and b=(b1,b2,b3). Can you write your two vectors in this form?
   
   

   Hold on.. this doesn't agree with what you stated above. Have another think...

    

   cristo, May 13, 2008
7. May 13, 2008 #6

   gtfitzpatrick

   

   xi+yj+zk.k so this is x0+y0+z1 = z?

    

   gtfitzpatrick, May 13, 2008
8. May 13, 2008 #7

   cristo

   

   Staff Emeritus

   Science Advisor

   Yup, that's correct.

    

   cristo, May 13, 2008
9. May 13, 2008 #8

   gtfitzpatrick

   

   thanks a mill

    

   gtfitzpatrick, May 13, 2008
10. May 13, 2008 #9

    cristo

    

    Staff Emeritus

    Science Advisor

    No problem!

     

    cristo, May 13, 2008

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