1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Dot product with 2 variables

  1. Jun 2, 2016 #1
    1. The problem statement, all variables and given/known data
    This problem actually has 2 parts.
    For vectors a= (2,p,8) and b= (q,4,12), determine the values of p and q so that the vectors are a)perpendicular b) collinear

    textbook answer: a) p= 1 and q= -50 (answers may vary) b) p= 8/3 and q=3

    2. Relevant equations
    a*b = 0

    a*b = a1b1 + a2b2 + a3b3

    3. The attempt at a solution

    So for the first part, I used a*b = 0 and I don't know how to do the second part

    a*b = 0
    (2,p,8)*(q,4,12) = 0
    2q + 4p + 96 =0

    I tried isolating p and q and substituting them but I end up with 0.
     
  2. jcsd
  3. Jun 2, 2016 #2

    Orodruin

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    First part: What do you mean by "end up with zero"? You are supposed to pick p and q so that the inner product is zero.

    Second part: What does it mean for two vectors to be collinear?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Dot product with 2 variables
  1. Dot product (Replies: 1)

  2. Dot product (Replies: 5)

  3. Dot product (Replies: 1)

Loading...