Page 2 of 2 FirstFirst 12
Results 16 to 29 of 29

Thread: Volume Problems

  1. #16
    Member
    Joined
    Nov 2010
    Posts
    102
    Thank you, everything makes sense now.
    Follow Math Help Forum on Facebook and Google+

  2. #17
    Member
    Joined
    Nov 2010
    Posts
    102
    So for part a I get the volume to be 157.6 Inches cubed, and for part b I still need to figure out the volume of the football using the equation of the parabola, is there a formula I need in order to relate the two equations ?
    Follow Math Help Forum on Facebook and Google+

  3. #18
    MHF Contributor
    Joined
    Mar 2010
    From
    Florida
    Posts
    3,093
    Thanks
    10
    You can integrate to find volume.
    Follow Math Help Forum on Facebook and Google+

  4. #19
    Member
    Joined
    Nov 2010
    Posts
    102
    Would my limits be -5.5 and 5.5 ?
    Follow Math Help Forum on Facebook and Google+

  5. #20
    MHF Contributor
    Joined
    Mar 2010
    From
    Florida
    Posts
    3,093
    Thanks
    10
    You could do 0, 5.5 and multiple by 2. Also, use the volume integral formulas. Regular integration solves area.
    Follow Math Help Forum on Facebook and Google+

  6. #21
    Member
    Joined
    Nov 2010
    Posts
    102
    volume integral formulas ? where do i find them ? or the right one ?
    Follow Math Help Forum on Facebook and Google+

  7. #22
    MHF Contributor
    Joined
    Mar 2010
    From
    Florida
    Posts
    3,093
    Thanks
    10
    \displaystyle V=\pi\int_{a}^{b}[f(x)]^2dx
    Follow Math Help Forum on Facebook and Google+

  8. #23
    Member
    Joined
    Nov 2010
    Posts
    102
    Thank you.
    Follow Math Help Forum on Facebook and Google+

  9. #24
    Member
    Joined
    Nov 2010
    Posts
    102
    Ok so when I evaluate my Volume I get a really huge number 3000 something which I know isn't right. This is what I evaluate. 2pi* the integral from 0 to 5.5 of ((-21)/2(5.5)^2pi (x^2)+ 21/2pi))^2dx. When I put that in my calculator and integrate I get a huge number. A friend of mine suggested I try a quad regression but I don't know how to do that on the calculator. Please tell me what I did wrong.
    Follow Math Help Forum on Facebook and Google+

  10. #25
    MHF Contributor
    Joined
    Mar 2010
    From
    Florida
    Posts
    3,093
    Thanks
    10
    I obtained 77 when I integrated it. Show your steps.
    Follow Math Help Forum on Facebook and Google+

  11. #26
    Member
    Joined
    Nov 2010
    Posts
    102
    I did show you my steps. ok I get for the equation Y = (21/2pi) - (21/2pi(5.5)^2) x^2. and then when I put that into the Volume formula I just move 2pi out front and square f(x) I put the whole function into my calculator and I use my calulator to integrate from 0 to 5.5 I get 3000 something
    Follow Math Help Forum on Facebook and Google+

  12. #27
    Member
    Joined
    Nov 2010
    Posts
    102
    Never mind good sir. I was plugging it in to the calculator wrong. I get 77 too now. Thank you
    Follow Math Help Forum on Facebook and Google+

  13. #28
    MHF Contributor
    Joined
    Mar 2010
    From
    Florida
    Posts
    3,093
    Thanks
    10
    \displaystyle 2\pi\int_{0}^{5.5}\left(\frac{21}{2\pi}-\frac{21}{2\pi *5.5^2}*x^2\right)dx=21\left[x]^{5.5}_0-\frac{21}{5.5^2}\left[\frac{x^3}{3}\right] _0^{5.5}

    \displaystyle = 21*5.5-\frac{21}{5.5^2}\left[\frac{5.5^3}{3}\right]=77
    Last edited by dwsmith; Nov 29th 2010 at 04:14 PM.
    Follow Math Help Forum on Facebook and Google+

  14. #29
    Member
    Joined
    Nov 2010
    Posts
    102
    Yes yes thank you once again.
    Follow Math Help Forum on Facebook and Google+

Page 2 of 2 FirstFirst 12

Similar Math Help Forum Discussions

  1. Volume && Average Value Problems.
    Posted in the Calculus Forum
    Replies: 3
    Last Post: Sep 13th 2009, 04:58 PM
  2. Volume problems!!!
    Posted in the Calculus Forum
    Replies: 0
    Last Post: Feb 5th 2009, 12:52 PM
  3. volume problems!!
    Posted in the Calculus Forum
    Replies: 1
    Last Post: Jan 31st 2009, 04:24 PM
  4. Some volume problems
    Posted in the Calculus Forum
    Replies: 0
    Last Post: Nov 5th 2008, 08:47 AM
  5. 2 Volume Problems
    Posted in the Calculus Forum
    Replies: 1
    Last Post: Feb 10th 2007, 06:45 PM

Search Tags


/mathhelpforum @mathhelpforum