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 arc length problem

  1. Sep 30, 2009 #1
    1. The problem statement, all variables and given/known data
    Find Arc Length:
    r(t)=t^3 i+tj+(1/2)[tex]\sqrt{6}[/tex]t^2k 1[tex]\leq[/tex]t[tex]\leq[/tex]3

    2. Relevant equations
    The arc length formula:
    integrate: sqrt((dx/dt)^2+(dy/dt)^2+(dz/dt)^2) dt

    3. The attempt at a solution
    I can find the derivative and plug into the formula, it's just the simplification that is absolutely stumping me. I haven't done this for a long time, which is always why my TeX is horribly put together.

    Any help is greatly appreciated. I've gotten to here so far:

    [tex]\int_1^3 \! \sqrt{9t^4+1+6t^2} \, dt.[/tex]
  2. jcsd
  3. Sep 30, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    The expression under the square root is a perfect square. Factor it!
  4. Oct 1, 2009 #3
    Thank you. I'm sorry for the nonsensical post, I guess I was way too tired to not have that jump out at me.

    Again, thank you.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook