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Homework Help: Grade 10 physics.

  1. Jul 25, 2007 #1
    1. The problem statement, all variables and given/known data
    ok heres the question

    A speed boat travels at 6.0 m/s [E] for 90s and then accelerates uniformly at 2.0 m/s² [E] for 5.0s. Caculate the displacement of the speedboat

    2. Relevant equations
    is this the formula i am suppose to use for this question?

    Delta D= V1*Delta T+1/2*A(Delta T)²

    note that the a in that formula is suppose to be vector acceleration.

    for the time do i just add up 90 seconds and 5 seconds?
  2. jcsd
  3. Jul 25, 2007 #2


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    No, you should look at the question in 2 parts, the first being the displacement over the first 90 seconds at constant speed (no acceleration), and the second part being the displacement over the next 5 seconds at the given acceleration and initial speed. Then add 'em up. You can't do it all at once, since the acceleartions are different over the noted time periods.
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