Results 1 to 7 of 7

Math Help - Variation problem

  1. #1
    Junior Member
    Joined
    Dec 2010
    Posts
    31

    Variation problem

    So Im having a hard to remembering how to work this out. Here is the problem:


    The weight of a liquid varies directly as its volume V. If the weight of the liquid in a cumbical container 4cm on a side is 128 g, find the weight of the liquid in a cubical container 3cm on a side.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Nov 2010
    From
    Staten Island, NY
    Posts
    451
    Thanks
    2
    This is a simple ratio:

    weight 128 x
    volume 64 27

    64x = (128)(27)
    x = 54

    Note that we cubed 4 and 3 because these are lengths of sides, and the weight varies directly as its VOLUME.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Dec 2010
    Posts
    31
    where did the 27 come from ?

    nvm you cubed the 3.. thanks
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member
    Joined
    Nov 2010
    From
    Staten Island, NY
    Posts
    451
    Thanks
    2
    3 is the length of a side, so the volume is 3^3 = 27.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Dec 2010
    Posts
    31
    What about this one:



    The gravatational attraction A between two masses varies inversely as the square of the distance between them. The force of attraction is 9 lb when the masses are 2 ft apart, what is the attraction when the masses are 6 ft apart?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Senior Member
    Joined
    Nov 2010
    From
    Staten Island, NY
    Posts
    451
    Thanks
    2
    In a direct variation problem (like the earlier one) you set quotients equal to each other. In an inverse variation problem (like this last one) you set products equal to each other.

    (9)(4) = (x)(36)

    So x = 1

    Note that we squared 2 and 6.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Junior Member
    Joined
    Dec 2010
    Posts
    31
    Ok cool thanks man
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. variation problem
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: December 9th 2010, 08:53 AM
  2. Variation problem
    Posted in the Algebra Forum
    Replies: 1
    Last Post: December 2nd 2010, 01:33 AM
  3. Variation Worded Problem
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 14th 2009, 05:09 AM
  4. Problem of direct variation
    Posted in the Algebra Forum
    Replies: 1
    Last Post: April 14th 2008, 01:22 AM
  5. A variation problem
    Posted in the Advanced Applied Math Forum
    Replies: 3
    Last Post: April 13th 2008, 11:23 PM

Search Tags


/mathhelpforum @mathhelpforum