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\noindent {\bf Problem statement} An object is moving along the
parabola $y=3x^2$.

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\noindent a) When it passes through the point $(2,12)$, its
``horizontal'' velocity is ${dx\over dt}=3$. What is its ``vertical''
velocity at that instant?

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\noindent b) If it travels in such a way that ${dx\over dt}=3$ for all
$t$, then what happens to ${dy\over dt}$ as $t\to+\infty$?

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\noindent c) If, however, it travels in such a way that ${dy\over dt}$
remains constant, then what happens to ${dx\over dt}$ as $t\to+\infty$?









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