1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Vector components hard!

  1. Sep 3, 2005 #1
    hi all got some problems with vectors so waswondering if anyone can check what i've done
    is correct thanks
    question1.

    find the vector component of 2i+j-k in the direction of i-3j+2k
    basically i use the rule
    a=(v*w^)*w^
    w^= i-3j+2k / sqrt(14)

    thus v=2i+j-k
    therefore a=(2i+j-k)*( i-3j+2k / sqrt(14) ) * (i-3j+2k / sqrt(14))
    a= [2(1)-3(1)-1(2) /sqrt(14)] * [i-3j+2k / sqrt(14)]
    a= -3/sqrt(14)* i-3j+2k / sqrt(14)

    thus the vector componentis a=-3/14( i-3j+2k) ???

    2. find the parametric equationsof the straightline of intersection of the planes
    x-2y+3z=5
    3x+y-2z=1

    i used gaussian elimination and got the tableu
    1 -2 3 | 5
    3 1 -2 | 1 R2-3R1

    1 -2 3 | 5
    0 7 -11| -14

    x-2y+3z=5
    7y-11z=-14
    z=t

    sub z=t into 7y-11z=-14
    y=11t/7 - 2

    sub y=11t/7 - 2 into x-2y+3z=5
    x= 5 + 1/7t

    therefore are the parametric equations
    x= 5 + 1/7t
    y=11t/7 - 2
    z=t

    ??
    thanks all
     
  2. jcsd
  3. Sep 3, 2005 #2

    StatusX

    User Avatar
    Homework Helper

    1. You found the projection vector along w, but it sounds like they just wanted the length of this vector. That is, just [itex]\vec v \cdot \hat w[/itex]. Think of it like this: if you rearranged your axes so that w pointed along the new x axis, what would be the new x component of v?

    2. The easiest way to check this is to plug x, y, and z back into the two plane equations and see if they solve them for all t (ie, t drops out and you get something like 1=1).
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook




Loading...
Similar Threads for Vector components hard Date
Inelastic 2D Collision with Vector Components Feb 26, 2018
Electric field vector in component form Jan 22, 2018
Kinematics -- flying a plane in the wind to a destination Jan 12, 2018
Vectors problem Nov 25, 2017