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!

Vectors in the direction of axis

  1. Jan 24, 2006 #1
    I have been having a debate that a vector in the positive x-direction must not have a y component other than 0. What are the other opinions on this wording and other possible wordings to mean that a vector is on the same line as an axis?
     
  2. jcsd
  3. Jan 24, 2006 #2
    umm you waited 10 minutes on an open forum? perhaps you should reword what you are asking.

    "what words to mean that a vector is on the same line as an axis"...hmm how about none ...lets use variables (x,y,z) thats for any axis...now by your wording i'd assume you meant a standard axis like x-axis,y-axis,z-axis or ei,ej,ek. So (a,0,0) and (0,b,0) and (0,0,c) where a,b,c!=0 all lie on their respective standard axis.
    now you also asked about "positive x-direction vector" ...any vector with the x-component >0 is considered such a vector regardless of the other 2 components. with the other 2 components=0 you get a standard axis vector. x-axis,y-axis,z-axis or ei,ej,ek.
     
  4. Jan 24, 2006 #3
    I have been having a debate that a vector in the positive x direction must not have a y component other than 0. Is that view correct or do all vectors with a positive x component "point in the positive x direction"? What are the other opinions on this wording and other possible wordings to mean that a vector is on the same line as an axis? My professor uses the meaning with the idea that a vector in the positive x direction points in the same direction as the positive x axis so it is similar to saying a vector in the positive x axis direction.
     
    Last edited: Jan 24, 2006
  5. Jan 24, 2006 #4
    I'll rephrase it slightly,

    I have been having a debate that a vector in the positive x direction must not have a y component other than 0. Is that view correct or do all vectors with a positive x component "point in the positive x direction"? What are the other opinions on this wording and other possible wordings to mean that a vector is on the same line as an axis? My professor uses the meaning with the idea that a vector in the positive x direction points in the same direction as the positive x axis so it is similar to saying a vector in the positive x axis direction.
     
    Last edited: Jan 24, 2006
  6. Jan 24, 2006 #5
    although it is vague, it is reasonable to assume that when a vector is in the positive x direction it only has a component in the x axis. I see no need to be pedantic about it.
     
  7. Jan 24, 2006 #6

    Tide

    User Avatar
    Science Advisor
    Homework Helper

    If a vector has a y component then it is not pointing in the x direction. Also, a vector pointing in the x direction is parallel to the x axis.
     
  8. Jan 24, 2006 #7

    Tide

    User Avatar
    Science Advisor
    Homework Helper

    You should only post your question in one area. Your other posting has already been answered.
     
  9. Jan 24, 2006 #8

    rcgldr

    User Avatar
    Homework Helper

    This is more of a language / logic issue:

    The statement "a vector in the positive x axis" implies the vector has no other component.

    A "vector with a component in the x axis" implies that the vector may or may not have a component along one or more other axis.
     
  10. Jan 24, 2006 #9

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    This thread has been merged, but I haven't pruned the postings. So things may appear out of place.

    Please DO NOT do multiple post (read our Guidelines if you have forgotten).

    Zz.
     
  11. Jan 25, 2006 #10
    Hi everyone, i'm having trouble calculating a vector direction that my schools online homework thing will accept, and i don't know why and i'm going nuts cause this stuff is easy!

    My work found the resultant vector to be:

    -13.17 i - 26.48 j , with a magnitude of 29.5772

    This online homework thing accepted my magnitude as the correct answer for this problem, which means my vector addition was ok. My problem is in finding whats wrong with how i determine the direction for the next problem that uses the answer from this one.

    Can someone explain to me that "Note:"?

    my answer for this was 116.441 degrees when i tried one way, (solving for theta when i subbed the x component of the vector and the magnitude into x = R cos(theta) as x = Magnitude*cos(theta)). I also tried adding 180 to that answer in case that crazy note meant to do that, and i tried the arctan(y component / x component) = 63.56 degrees, which the site also said was wrong answer. I am really confussed on this.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Vectors in the direction of axis
  1. Direction of vectors (Replies: 1)

  2. Vector direction? (Replies: 7)

Loading...