A web page designer creates an animation in which a dot on a computer screen has a position of $\vec{r}=<4.0 \mathrm{cm}+$ $\left(2.5 \mathrm{cm} / \mathrm{s}^{2}\right) t^{2} > \hat{\boldsymbol{\imath}}+(5.0 \mathrm{cm} / \mathrm{s}) t \hat{\boldsymbol{J}}$ (a) Find the magnitude and direction of the dot's average velocity between $t=0$ and $t=2.0 \mathrm{s} .$ (b) Find the magnitude and direction of the instantaneous velocity at $t=0, t=1.0 \mathrm{s},$ and $t=2.0 \mathrm{s} .$ (c) Sketch the dot's trajectory from $t=0$ to $t=2.0 \mathrm{s},$ and show the velocitiescalculated in part (b).

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