Answer
Velocity of the object $= 11$ m s$^{-1}$ and acceleration of the object is $= -6$ m s$^{-2}$.
Work Step by Step
1. Find $v(3)$
$v(t) = 20 - t^{2}$
$v(3) = 20 - (3)^{2}$
$= 20 - 9$
$= 11$ m s$^{-1}$
2. Find $a(3) = v'(3)$
$v'(t) = -2t$
$a(3) = -2(3)$
$= -6$ m s$^{-2}$
