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Homework Help: Calc Based Physics problem

  1. Jun 5, 2008 #1
    1. The problem statement, all variables and given/known data

    An objects position as a function of time is given by r=12ti+(15t-5.0t^2)jm, where t is time in seconds. A: what is the onject's position at t=2 s. B what is its average velocity in the interval from t=o to t=2.0s.C: what is its instantaneous velocity at t=2?

    2. Relevant equations

    Derivative:12i+(15-10t)

    V=change in r/change t

    3. The attempt at a solution
    A: simply plug 2 in for t in the original equation
    B:take the derivative of the problem and plug in 2 for t
    C: Dont really know . . .
     
  2. jcsd
  3. Jun 5, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    OK.
    No derivatives needed, since you want the average velocity. (Use the formula you quoted.)
    Here's where you need a derivative.
     
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