Results 1 to 4 of 4
Like Tree1Thanks
  • 1 Post By TD!

Math Help - HW typo--

  1. #1
    Newbie
    Joined
    Jan 2006
    Posts
    16

    HW typo--

    A new motion detector is used to graph the position of a sports car. If the themotion detector is not callibrated properly, it might give unrealistic graph data. The position of the car is described by the function S= 2t^3-21t^2 + 60t, tE [0,6], where s is measured in meters and t in seconds. it is known the largest acceleration is 12 m/s ^2.


    Can some one double check this ? and help me

    a) WHat is its initial velocity? ---60
    b)When is the car at rest? t=0
    c)When is the car moving in the forward direction? ******* Can someone explain to me how to get this?
    d)draw a diagram ----
    e)Find the total distance traveled by the car in the first 6 seconds----36
    f)Find the max acceleration of the car? a = 12t-42 a=30
    Follow Math Help Forum on Facebook and Google+

  2. #2
    TD!
    TD! is offline
    Senior Member
    Joined
    Jan 2006
    From
    Brussels, Belgium
    Posts
    405
    Thanks
    3
    Quote Originally Posted by tnkfub
    a) WHat is its initial velocity? ---60
    b)When is the car at rest? t=0
    c)When is the car moving in the forward direction? ******* Can someone explain to me how to get this?
    d)draw a diagram ----
    e)Find the total distance traveled by the car in the first 6 seconds----36
    f)Find the max acceleration of the car? a = 12t-42 a=30
    Well, a is correct but how can b be correct then? If the initial speed (at t = 0) is 60m/s, then the car can't be at rest at t = 0. The car is at rest when v = 0, take it from there.
    For c, when v is positive: the car moves forward (and backward when v < 0).
    Draw the diagram yourself, it'll help for e as well, f seems to be ok.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jan 2006
    Posts
    16
    thanks for the help TD

    b)

    S= 2t^3-21t^2 + 60t
    v = 6t^2-42t+60
    v= 6(t^2-7t+10)
    v= 6(t-2)(t-5)
    t= 2 and 5 sec

    does that make sense that v is 0 at two points of time?

    This doesnt look right >> :/
    Follow Math Help Forum on Facebook and Google+

  4. #4
    TD!
    TD! is offline
    Senior Member
    Joined
    Jan 2006
    From
    Brussels, Belgium
    Posts
    405
    Thanks
    3
    Quote Originally Posted by tnkfub
    thanks for the help TD

    b)

    S= 2t^3-21t^2 + 60t
    v = 6t^2-42t+60
    v= 6(t^2-7t+10)
    v= 6(t-2)(t-5)
    t= 2 and 5 sec

    does that make sense that v is 0 at two points of time?

    This doesnt look right >> :/
    Why not? If you made a good diagram, you can see why.
    Thanks from jonwen97
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Mathematical Logic by Cori and Lascar : Possible typo?
    Posted in the Discrete Math Forum
    Replies: 6
    Last Post: June 2nd 2011, 04:57 PM
  2. Wondering if this is a typo?
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: April 30th 2009, 01:01 PM

Search Tags


/mathhelpforum @mathhelpforum