Chapter 11 - Vectors and Vector-Valued Functions - 11.7 Motion in Space - 11.7 Exercises - Page 826: 8

a) $\textbf{v}(t) =<5t, 12t>$; Speed = $13t$ b) $\textbf{a}(t) = <5, 12>$

$\textbf{r}(t) = $ $\textbf{v}(t) = \textbf{r}'(t) =<5t, 12t>$ Speed = $|\textbf{v}(t)| = \sqrt {(5t)^2+(12t)^2} = 13t$ $\textbf{a}(t) = \textbf{v}'(t) = <5, 12>$