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!

Collinear vector help

  1. Jun 25, 2005 #1
    The position vectors of A, B and C relative to an origin O are [tex]-I+pj[/tex], [tex]5i+9j[/tex] & [tex]6i+8j[/tex] respectively. Determine the value of p for which A, B & C are collinear.
     
    Last edited: Jun 25, 2005
  2. jcsd
  3. Jun 25, 2005 #2
    Have you learned any coordinate geometry at school?
     
  4. Jun 25, 2005 #3
    Yes I have.
     
  5. Jun 25, 2005 #4
    So you may instead assign the coordinates (-1,p) to the position vector -i + pj, (5,9) to the position vector 5i + 9j and (6,8) to the position vector 6i + 8j.

    If three points are collinear, this means that the gradient between any two points of the three is the same.
     
  6. Jun 25, 2005 #5
    Thank you!
     
  7. Jun 25, 2005 #6
    One more question.
    a) The vector [tex]\displaystyle \overrightarrow{OA}[/tex] has magnitude 100 and has the same direction as [tex]\displaystyle \left(\begin{array}{cc}7\\24\end{array}\right)[/tex]. Express [tex]\displaystyle \overrightarrow{OA}[/tex] as a column vector.
    b) The vector [tex]\displaystyle \overrightarrow{OB}[/tex] is [tex]\displaystyle \left(\begin{array}{cc}24\\99\end{array}\right)[/tex]. Obtain the unit vector in the direction of [tex]\displaystyle \overrightarrow{AB}[/tex].
     
  8. Jun 25, 2005 #7
    You need to show evidence of some work. Do you know what unit vectors are?
     
  9. Jun 25, 2005 #8
    Yes I do know.
     
  10. Jun 25, 2005 #9
    Then you should be able to solve both of those problems..
     
  11. Jun 25, 2005 #10
    If I did, I wouldn't have posted them. :bugeye:
     
    Last edited: Jun 25, 2005
  12. Jun 25, 2005 #11
    First of all, find the magnitude of the vector [tex]\displaystyle \left(\begin{array}{cc}7\\24\end{array}\right)[/tex]. What is it?

    Do you know how to calculate the vector [tex]\displaystyle \overrightarrow{AB}[/tex]? (Hint: use information from a)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Collinear vector help
  1. Collinear vectors (Replies: 2)

  2. Vectors Help (Replies: 12)

  3. Vectors Help (Replies: 12)

  4. Help with vectors? (Replies: 5)

Loading...