Results 1 to 2 of 2

Math Help - a question about differentiation

  1. #1
    Junior Member
    Joined
    Jun 2008
    Posts
    53

    a question about differentiation

    P is a point 22m due east of a fixed point O and Q is a point 14m due south of O. A particle A starts at P and moves towards O at a speed of 4m/s while a particle B starts at Q at the same time as A and moves towards O at a speed of 3m/s. Find an expression for the distance between A and B t seconds after the start. Hence, find the value of t when the distance between A and B is a minimum and find this minimum distance.



    i can't figure out how to relate them and make an expression.
    i think i can do the latter part once the expression is found.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Nov 2008
    From
    France
    Posts
    1,458
    Hi

    First define a referential : for instance O as origin, x axis = (OP) with P abscissa = 22, y axis = (OQ) with Q ordinate = -14, and time=0 when the particles start. Then P(22,0) and Q(0,-14).

    The first particle speed is \overrightarrow{v_1} = -4\overrightarrow{i}
    Integrating gives \overrightarrow{OM_1}= (-4t+22)\overrightarrow{i}

    Same method for the second particle.

    Then \overrightarrow{M_1M_2} = -\overrightarrow{OM_1} + \overrightarrow{OM_2}

    Then the distance M_1M_2
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. ln differentiation question
    Posted in the Calculus Forum
    Replies: 1
    Last Post: December 7th 2011, 02:47 PM
  2. Replies: 6
    Last Post: July 21st 2010, 07:20 PM
  3. differentiation question 2
    Posted in the Calculus Forum
    Replies: 1
    Last Post: August 30th 2009, 02:22 PM
  4. Differentiation question
    Posted in the Calculus Forum
    Replies: 7
    Last Post: December 10th 2008, 05:54 PM
  5. Differentiation Question...
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 2nd 2008, 04:53 AM

Search Tags


/mathhelpforum @mathhelpforum