The position of a particle is

r$($t$)=(7\mathrm{.}0$t$26\mathrm{.}0+8\mathrm{.}0$t$3$k$)$ m$.$

$($a$)$

What is the velocity of the particle at $0$ s and at $1\mathrm{.}0$ s $($in m$/$s$)?($Express your answers in vector form.$)$

v$(0$ s$)$

$=$

m$/$s

v$(1\mathrm{.}0$ s$)$

$=$

m$/$s

$($b$)$

What is the average velocity between $0$ s and $1\mathrm{.}0$ s $($in m$/$s$)?($Express your answer in vector form.$)$

vavg $=$

m$/$s