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Homework Help: What is the time taken for these 2 cars to meet?

  1. Sep 18, 2008 #1
    1. The problem statement, all variables and given/known data

    Two cars, P and Q, are 1400m apart.
    P is travelling at 15 ms-1, Q is accelerating from rest at 5.0 ms-2
    They are travelling opposite direction(i.e. they are facing each other), what is the time taken for them to meet?
    Also, what is the distance travelled by each car before meeting each other?

    2. Relevant equations

    a = [tex]\frac{v-u}{t}[/tex]

    3. The attempt at a solution

    I got a = 5t, but it did not seem to help much...
    Do I have to draw a graph for this question?
  2. jcsd
  3. Sep 18, 2008 #2
    No, just write out the position dependence over time for the two cars and equate. Assume Car 1 to b at x=0 and the second car to be at x=1400
    S=u*t+0.5*a*t*t (for the accelerated motion) (Use negative sign for acceleration)
    S=v*t (for the constant velocity motion)
  4. Sep 18, 2008 #3
    Thank you!
    I forgot I can use area under a V-T graph of constant acceleration (and sub v=at) to get the total distance travelled by car Q.
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