Results 1 to 5 of 5

Math Help - Work done to lift chain w/ weight attached

  1. #1
    Newbie
    Joined
    Sep 2008
    Posts
    13

    Work done to lift chain w/ weight attached

    I'm working on a few questions that apply calculus to physics questions.
    I seem to be having issues with this one question(been at it for awhile)
    ---------------
    An anchor weighing 100lb in water is attached to a chain weighing 3lb/ft in water. Find the work done to haul the anchor and chain to the surface of the water from a depth of 25ft.
    ----------------

    So this is what i've attempted:

    Knowing that  W = F * D and that in these units a lb is a force unit,

    I've sliced the chain horizontally so it has thickness  \Delta y

    So my next step is to calculate the work done on this strip to lift it, plus the weight of the anchor, to the top. Then ill integrate the formula i get for the work on the strip across the total length of the chain. That is, from 0 to 25.

    My problem is getting the work done on this strip. Work = Force * Distance
    or in this case Work = Mass * Distance.
    I know that Distance will be = (25-y) but what is the mass of the chain? It is obviously 3lb/ft *  \Delta y but how do i account for the anchor at the bottom? Must i account for the remaining chain attached below the strip?

    Any quick help here is greatly appreciated.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Sep 2008
    Posts
    13
    I know this might be more physics than calculus is - there a better place to be posting this?
    Last edited by mkelly09; October 20th 2008 at 02:58 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Sep 2008
    Posts
    13
    bump.. anyone have any clues for me?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Sep 2008
    Posts
    13
     int_{r=0}^{r=25} (100 + 3 (r)

    this would be the answer.. thanks anyways guys!
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,698
    Thanks
    454
    total work = work to raise the chain + work to raise the anchor

    the force required to raise the anchor is not variable ...

    W_{total} = \int_0^{25} (25-y)3\, dy + 2500
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. The weight of H(X) does not exceed the weight of X?
    Posted in the Differential Geometry Forum
    Replies: 0
    Last Post: October 13th 2011, 09:59 AM
  2. How much force to lift a car?
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: March 25th 2011, 04:10 PM
  3. work done by lifting block attached to spring
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 1st 2010, 10:01 PM
  4. Find Length of Ski Lift
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: September 7th 2008, 08:19 AM
  5. Replies: 1
    Last Post: December 4th 2007, 03:45 PM

Search Tags


/mathhelpforum @mathhelpforum