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Homework Help: Car moving down road

  1. Sep 29, 2012 #1
    car moving down road....

    1. The problem statement, all variables and given/known data
    A car is moving down a road at 45 km/hr when it runs out of gas. How far does the car move if it takes 6.0s to roll to a stop?

    2. Relevant equations
    x=(vi+vf)/2 *t I tried this equation, but I got the answer of 135 m. It says the answer is 37.5 m in the answers given by the teacher.
    3. The attempt at a solution

    I set it up this way:

    vi: 45 km/hr
    vf: 0
    t= 6.0 s
    x= (45+0)/2 * 6.0 = 135 m

    I want to know what I'm doing wrong, am I using the wrong equation? Thanks.
  2. jcsd
  3. Sep 29, 2012 #2


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    Re: car moving down road....

    I suspect that you need to convert the velocity to m/sec.
  4. Sep 29, 2012 #3
    Re: car moving down road....

    yeh it worked, i got the right answer ! :approve: :D

    thankyou! :)
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