Motion in a plane

The position of a particle is
given by

r i j k = + + 3.0t
ˆ .
ˆ . 2 0 5 0 ˆ
2
t
where t is in seconds and the
coefficients have the proper units for r to
be in metres. (a) Find v(t) and a(t) of the
particle. (b) Find the magnitude and
direction of v(t) at t = 1.0 s.