Results 1 to 4 of 4

Math Help - Related Rates help

  1. #1
    Newbie
    Joined
    Jan 2008
    Posts
    10

    Related Rates help

    Hi I am in the middle of solving this provlem however, since I am only given a limited amount of information I am confused as to how to solve it.

    "Two cars start moving from teh same point. One travels south at 60 mi/h and the other travels west at 25 mi/h. At what rate is the distance between the cars increasing two hours later?"

    So far I have the equation..
    (z^2) = (x^2) + (y^2)

    I know dy/dt = 60 mi/h and dx/dt = 25 mi/h.

    I implicity differentiated the first equation and ended up with:
    dz/dt = (50x +120y)*(1/2z)

    Since I do not know what x or y is I am unable to find the rate the distance between the two cars is increasing.

    Thank you so much for your help!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    GAMMA Mathematics
    colby2152's Avatar
    Joined
    Nov 2007
    From
    Alexandria, VA
    Posts
    1,172
    Awards
    1
    Quote Originally Posted by aquaglass88 View Post
    Hi I am in the middle of solving this provlem however, since I am only given a limited amount of information I am confused as to how to solve it.

    "Two cars start moving from teh same point. One travels south at 60 mi/h and the other travels west at 25 mi/h. At what rate is the distance between the cars increasing two hours later?"

    So far I have the equation..
    (z^2) = (x^2) + (y^2)

    I know dy/dt = 60 mi/h and dx/dt = 25 mi/h.

    I implicity differentiated the first equation and ended up with:
    dz/dt = (50x +120y)*(1/2z)

    Since I do not know what x or y is I am unable to find the rate the distance between the two cars is increasing.

    Thank you so much for your help!
    Two hours later, the one car is 120 miles south (y = 120), and the other car is 50 miles west (x = 50).

    z^2 = 120^2+50^2

    Plug x, y, and z into your dz/dt equation.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jan 2008
    Posts
    10
    Oh ok I understand now! thank you so much!
    Follow Math Help Forum on Facebook and Google+

  4. #4
    GAMMA Mathematics
    colby2152's Avatar
    Joined
    Nov 2007
    From
    Alexandria, VA
    Posts
    1,172
    Awards
    1
    Quote Originally Posted by aquaglass88 View Post
    Oh ok I understand now! thank you so much!
    You are welcome AquaGlass!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Related Rates
    Posted in the Calculus Forum
    Replies: 1
    Last Post: October 26th 2009, 09:54 PM
  2. Rates and Related Rates!!
    Posted in the Calculus Forum
    Replies: 1
    Last Post: April 2nd 2008, 11:53 AM
  3. Another Related Rates
    Posted in the Calculus Forum
    Replies: 3
    Last Post: March 13th 2008, 07:32 AM
  4. Related Rates
    Posted in the Calculus Forum
    Replies: 6
    Last Post: March 12th 2008, 06:49 PM
  5. rates and related rates
    Posted in the Calculus Forum
    Replies: 2
    Last Post: October 29th 2007, 10:51 PM

Search Tags


/mathhelpforum @mathhelpforum