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: Exam question t/f

  1. Sep 13, 2012 #1

    Mdhiggenz

    User Avatar

    1. The problem statement, all variables and given/known data

    So I took my calc 3 exam today and had this question

    true or false

    magnitude ( v+v) = 2*magnitude( v)

    I put true.

    Thoughts?


    2. Relevant equations



    3. The attempt at a solution
     
    Mdhiggenz, Sep 13, 2012
  2. jcsd
    Phys.org - latest science and technology news stories on Phys.org
  3. Sep 13, 2012 #2

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    You got it correct. Were you just guessing?
     
    LCKurtz, Sep 13, 2012
  4. Sep 13, 2012 #3

    Mdhiggenz

    User Avatar

    No I did a problem where I had to solve for K in the magnitude give the value of v. Pretty much I took k from the magnitude and solved for it. So I was hoping the same thing applied here.
     
    Mdhiggenz, Sep 13, 2012
  5. Sep 13, 2012 #4

    skiller

    User Avatar

    Really? I don't see how this is correct.
     
    skiller, Sep 13, 2012
  6. Sep 13, 2012 #5

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    If ##\vec v = \langle a,b,c\rangle## what do you get for ##|\vec v|## and ##|2\vec v|##?
     
    LCKurtz, Sep 13, 2012
  7. Sep 13, 2012 #6

    skiller

    User Avatar

    Sorry, of course it's correct.

    I was having a senile moment when I was imagining the two vectors weren't the same! D'oh! :redface:
     
    skiller, Sep 13, 2012
  8. Sep 13, 2012 #7

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Don't feel to bad about that. My first reaction was the same because I was expecting the question to read u+v since, in my opinion, that would have been a better question. Only after I started my reply did I realize the OP had v+v.
     
    LCKurtz, Sep 13, 2012
  9. Sep 13, 2012 #8

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Did the same thing here. :smile:
     
    vela, Sep 13, 2012
  10. Sep 13, 2012 #9

    skiller

    User Avatar

    I obviously need to learn to read twice before posting. Something which you two are obviously better at than me! :smile:
     
    skiller, Sep 13, 2012
  11. Sep 13, 2012 #10

    Mark44

    User Avatar
    Insights Author

    Staff: Mentor

    If v happened to be perpendicular to itself, the original statement wouldn't be true.:tongue:

    (The zero vector not included, of course.)
     
    Mark44, Sep 13, 2012
  12. Sep 13, 2012 #11

    skiller

    User Avatar

    Now you've lost me!
     
    skiller, Sep 13, 2012
  13. Sep 13, 2012 #12

    Mark44

    User Avatar
    Insights Author

    Staff: Mentor

    Math humor...

    A nonzero vector can't be perpendicular to itself.
     
    Mark44, Sep 13, 2012
  14. Sep 13, 2012 #13

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    What if it's bent?
     
    LCKurtz, Sep 13, 2012
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook




Loading...
Similar Threads for Exam question Date
Fourier Series Exam Question Mar 10, 2013
Derivative question! Exam tomorrow, need to understand this asap! Oct 30, 2012
Exam question t/f 2 Sep 13, 2012
The ambiguous question came to my last week exam Mar 28, 2012