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Homework Help: Average velocity vector of non-uniform circular motion?

  1. Oct 29, 2016 #1
    1. The problem statement, all variables and given/known data
    A particle starting from rest revolves with uniformly increasing speed in a clockwise circle in an xy plane. The center of the circle is at the origin of an xy coordinate system. At t=0, the particle is at x=0.0m, y=2.0m. At t=2.0s, it has made one-quarter of a revolution and is at x=2.0m,y=0.0m.

    (a) Speed at t=2.0s?
    (b) Average velocity vector?
    (c) Average acceleration vector during this interval.

    2. Relevant equations

    $$a_{tan} = \frac{dv}{dt}$$
    $$a_R = \frac{v^2}{r}$$
    $$a = \sqrt{a^2_{tan}+a^2_{R}}$$

    3. The attempt at a solution

    $$r = 2$$
    $$d = \frac{2 \pi (2)}{4} = \pi$$
    $$v = \frac{\pi}{2}$$

    b, c) I don't know where to start because it's asking for a vector which implies that we need to calculate the "average angle" ?
  2. jcsd
  3. Oct 29, 2016 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Your answer for a) is wrong. what equations do you know for uniform acceleration? (Usually called the SUVAT equations.)
    Also, you should state the units in the answers.
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