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Homework Help: Particle Acceleration

  1. Jun 1, 2009 #1
    1. The problem statement, all variables and given/known data
    A particle moves in a plane with constant radial velocity (r dot) and constant angular velocity (theta dot). When the particle is at distance r from the origin, determine the magnitude of the acceleration.

    r dot = 4.3 m/s
    theta dot = 2.5 rad/s
    r = 3.1 m
    speed of the particle at r = 8.86 m/s

    2. Relevant equations
    v = (((r dot)^2)+((r*(theta dot))^2))^.5

    3. The attempt at a solution
    I have attempted to find the derivative of the above equation, but I am not sure if I am doing the derivate wrong.
  2. jcsd
  3. Jun 1, 2009 #2

    Andrew Mason

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    Science Advisor
    Homework Helper

    You have the right expression for the magnitude of v as a function of r. Take the derivative with respect to time. Since [itex]\dot r[/itex] is constant with time, what is its derivative?

    [tex]|a| = |dv/dt| = \frac{d}{dt}\sqrt{|\dot r|^2 + \omega^2r^2}[/tex]

  4. Jun 2, 2009 #3
    thanks for the help
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