Results 1 to 2 of 2

Math Help - Rate of Change

  1. #1
    Newbie
    Joined
    Mar 2008
    Posts
    16

    Rate of Change

    Can someone assist me with this one:

    A person obeserves an airplane directly overhead which moves at 500ft/sec at an altitue of 8000ft. The plane maintains constant altitude and horizontal velocity. What is the rate of change of the distance between the obeserver and the airplane after 12 seconds?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Eater of Worlds
    galactus's Avatar
    Joined
    Jul 2006
    From
    Chaneysville, PA
    Posts
    3,001
    Thanks
    1
    Did you draw a triangle. We can use Pythagoras.

    dx/dt=500, y=8000, dy/dt=0 because it remains constant.

    After 12 seconds, the plane will have travelled 6000 feet.

    D^{2}=x^{2}+y^{2}

    D\frac{dD}{dt}=x\frac{dx}{dt}+y\frac{dy}{dt}

    By Pythagoras, D=\sqrt{8000^{2}+6000^{2}}=10,000

    10,000\frac{dD}{dt}=6000(500)+8000(0)

    Solve for dD/dt.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: April 12th 2011, 10:51 AM
  2. rate change
    Posted in the Calculus Forum
    Replies: 1
    Last Post: July 11th 2008, 04:11 AM
  3. rate of change
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 20th 2008, 08:53 AM
  4. rate of change
    Posted in the Calculus Forum
    Replies: 9
    Last Post: May 3rd 2007, 10:39 AM
  5. Rate of change
    Posted in the Statistics Forum
    Replies: 2
    Last Post: April 18th 2007, 08:27 AM

Search Tags


/mathhelpforum @mathhelpforum