Results 1 to 4 of 4

Math Help - Derivaties in relation to velocity, speed,etc

  1. #1
    Member
    Joined
    Oct 2007
    Posts
    178

    Derivaties in relation to velocity, speed,etc

    Suppose that the distance an aircraft travels along a runway befoer takeoff is given by D=\frac {10t^2}{9} , where D is measured in meters from the starting point and t is measured in seconds from that time the brakes are released If the airplane will become airborne when its speed reaches 200 km/h, how long will it take to become airborne, and what distance will it have traveled by that time?

    Phew.


    Okay, I think

    1st find velocity (derivative of distance)
    v(t)= \frac {20t}{9}

    Then set 200= \frac {20t}{9}

    Then solve for t. T= 90 h

    2nd plug 90 for t in the original equation.

    and solve for t.

    t= 9000 km/h


    Yes? NO? Maybe so?

    Thank you!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member Singular's Avatar
    Joined
    Dec 2006
    From
    Solo, Java
    Posts
    57
    v(t) = dD/dt = 20t/9

    200*1000/3600 = 20t/9
    t = 25 seconds

    it takes 25 second before airborne

    the distance = 10(625)/9= 694,444444 meters
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Oct 2007
    Posts
    178
    Quote Originally Posted by Singular View Post
    v(t) = dD/dt = 20t/9

    200*1000/3600 = 20t/9
    t = 25 seconds

    it takes 25 second before airborne

    the distance = 10(625)/9= 694,444444 meters
    Where did 1000/3600 come from? How did you get 1000/3600?

    The rest I understand.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,805
    Thanks
    116
    Quote Originally Posted by Truthbetold View Post
    Where did 1000/3600 come from? How did you get 1000/3600?

    The rest I understand.
    Hello,

    the speed was given in \frac{km}{h}.

    1 km = 1000 m
    1 h = 3600 s

    Thus 200 \frac{km}{h} = 200\cdot \frac{1000m}{3600 s}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. acceleration - velocity & speed
    Posted in the Calculus Forum
    Replies: 7
    Last Post: November 12th 2008, 01:48 PM
  2. [SOLVED] speed & velocity
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: February 27th 2008, 12:13 PM
  3. speed velocity
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: February 23rd 2007, 08:35 AM
  4. speed and velocity
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: October 9th 2006, 04:54 AM
  5. velocity and speed
    Posted in the Calculus Forum
    Replies: 4
    Last Post: June 24th 2006, 05:59 AM

Search Tags


/mathhelpforum @mathhelpforum