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Homework Help: Kinematics question help please ?

  1. Sep 5, 2010 #1
    kinematics question help please :)?

    So I've tried to attempt this problem by finding possible things like time or velocity but it just does not come out right. Help is greatly appreciated :)

    Problem:

    At the instant the traffic light turns green, an automobile starts with a constant acceleration a of 2.0 m/s^2. At the same instant a truck is 13.4 m down the road and traveling with a constant speed of 9.3 m/s. (a) How far beyond the traffic signal will the automobile overtake the truck? (b) How fast will the automobile be traveling at that instant?

    heres some work I did:
    Truck:
    v=x/t
    9.3=13.4/t
    t= 1.44 s


    Thanks :)
     
    Last edited: Sep 5, 2010
  2. jcsd
  3. Sep 5, 2010 #2
    Re: kinematics question help please :)?

    If you know how far are the truck and the car from the traffic light at any moment, this problem is easy to solve.

    So, for the car you have

    [tex]x(t)=\frac{1}{2}at^2.[/tex]

    And for the truck

    [tex]x(t)=x_0+vt.[/tex]

    Now you just need to figure what is [itex]x_0[/itex] and what is the condition for the car and the truck to meet.
     
  4. Sep 5, 2010 #3
    Re: kinematics question help please :)?

    What is x(t)?
     
  5. Sep 5, 2010 #4
    Re: kinematics question help please :)?

    [itex]x(t)[/itex] is the function with [itex]t[/itex] as a variable. It tells you what is the distance [itex]x[/itex] from the traffic light at the time [itex]t[/itex].
     
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