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Homework Help: Determine the Velocity of the body with Velocity decreasing by v^2 = k/s

  1. Jan 30, 2013 #1
    1. The problem statement, all variables and given/known data
    A retarding force is applied to a body moving in a straight line so that, during an interval of its motion, its speed v decreases with increased position s according to the relation v2=k/s, where k is a constant. If the body has a forward speed of 1.8 in/sec and its position coordinate is 9.2 in at time t=0, determine the speed v at t=4.0 sec.

    2. Relevant equations

    v = ds/dt

    3. The attempt at a solution

    I'm honestly not sure how to start this question. Suggestions would be appreciated.
  2. jcsd
  3. Jan 30, 2013 #2

    rude man

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    Gold Member

    I would start with v = √(k/s) = ds/dt. k is easily gotten. Then get s(t) with the known boundary value, and finally substitute v = √(k/[s(t=4)].

    Hope that puts you on the right track.
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