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Homework Help: Calculus of vector function

  1. Jan 16, 2015 #1
    1. The problem statement, all variables and given/known data
    The position vector of a particle at time t is given by r(t)= 2sin(2t)i + cos(2t)j + 2tk where t >=0.

    2. Relevant equations
    v(t) = 4cos(2t)i - 2sin(2t)j + 2k
    speed = | v(t) | =√(16cos^2(2t)+4sin^2(2t)+4) = √(12cos^2(2t)+8)
    3. The attempt at a solution
    I found the velocity and speed, but I have no idea what to do to find out the maximum and minimum speed for this question, someone can teach me???
  2. jcsd
  3. Jan 16, 2015 #2


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    How do you usually find the extrema of a function?
  4. Jan 16, 2015 #3
    Things are easier in that the question is asking about scalar speed. What does it mean for the derivative when speed hits a peak/trough?
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