Results 1 to 8 of 8

Math Help - Rectilinear Motion problem

  1. #1
    Newbie
    Joined
    Feb 2009
    Posts
    5

    Rectilinear Motion problem

    for this position function discuss the motion along a horizontal line.

    Discuss the instantaneous velocity, acceleration, intervals when the particle in motion is moving to the right and left, intervals when the particle in motion is speeding up and slowing down.

    how would I do this? Im also suppose to sketch the motion of the particle at its appropriate position above the line of motion.

    f(x) = x^3/3-2x^2 + 3x +8

    Thanks
    Last edited by xswesx; February 12th 2009 at 08:49 AM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,370
    Thanks
    1314
    Quote Originally Posted by xswesx View Post
    For the following position function, discuss the motion along a horizontal line. Discuss the instantaneous velocity, acceleration, intervals when the particle in motion is moving to the right and left, intervals when the particle in motion is speeding up and slowing down.

    how would I do this? Im also suppose to sketch the motion of the particle at its appropriate position above the line of motion.

    f(x) = x^3/3-2x^2 + 3x +8

    Thanks
    You are clearly expected to know that the "instantaneous velocity" is the first derivative of f and the acceleration is the second derivative. Can you find the first and second derivatives of this function?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Feb 2009
    Posts
    5
    not really sure how, thanks
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,370
    Thanks
    1314
    Quote Originally Posted by xswesx View Post
    not really sure how, thanks
    What course is this for? It looks like a calculus problem.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Feb 2009
    Posts
    5
    can you show me how to find the first and second derivative?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Newbie
    Joined
    Feb 2009
    Posts
    5
    (x^3/3) - 2x^2 + 3x +8

    is it ok to multiply this whole function by 3 to get

    x^3 -6x^2 + 9x +24? and then do the first and second derivative?

    the (x^3/3) is giving me problems, can someone be kind enough to tell me how to find the derivative of this fraction?

    THanks
    Follow Math Help Forum on Facebook and Google+

  7. #7
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,370
    Thanks
    1314
    Quote Originally Posted by xswesx View Post
    (x^3/3) - 2x^2 + 3x +8

    is it ok to multiply this whole function by 3 to get

    x^3 -6x^2 + 9x +24? and then do the first and second derivative?
    No, that is now a different function. You could factor out the 1/3 and write it as (1/3)(x^3- 6x^2+ 9x+ 24) and then differentiate it. You need to know that the derivative of af(x) (a times the function f(x)) is af'(x) (a times the derivative of f).

    the (x^3/3) is giving me problems, can someone be kind enough to tell me how to find the derivative of this fraction?

    THanks
    The derivative of x^3 is 3x^2 so the derivative of x^3/3= (3x^2)/3= x^2.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Newbie
    Joined
    Feb 2009
    Posts
    5
    alright thanks, now the next step, original problem is

    f(x) = x^3/3-2x^2 + 3x +8

    first derivative: x^2 - 4x + 3 .... x = 3 x = 1
    second derivative: 2x - 4 .... x = 2

    s(0) = 8
    s(1) = 9 1/3
    s(2) = 8 2/3
    s(3) = 8

    so now

    time velocity acceleration speed
    0 < x <1
    1< x < 2
    2< x < 3
    x> 3

    how would I find out the velocity acceleration speed?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Rectilinear Motion
    Posted in the Calculus Forum
    Replies: 3
    Last Post: August 11th 2010, 05:48 PM
  2. Rectilinear Motion Help
    Posted in the Calculus Forum
    Replies: 2
    Last Post: January 29th 2010, 02:50 PM
  3. Rectilinear Motion
    Posted in the Calculus Forum
    Replies: 2
    Last Post: December 25th 2008, 04:18 PM
  4. Rectilinear motion using Antiderivatives
    Posted in the Calculus Forum
    Replies: 3
    Last Post: March 25th 2007, 01:24 PM
  5. Rectilinear Motion
    Posted in the Calculus Forum
    Replies: 2
    Last Post: February 20th 2007, 01:49 PM

Search Tags


/mathhelpforum @mathhelpforum