Answer:
65 m/s north
Explanation:
The velocity of an object is given by:
[tex]v=\frac{d}{t}[/tex]
where
d is the displacement of the object
t is the time interval needed for the displacement
For the rocket in this problem,
d = 390 m north
t = 6 s
So the velocity is
[tex]v=\frac{390}{6}=65 m/s[/tex] north
It is important to keep in mind that velocity is a vector, so it both has a magnitude (65 m/s) and a direction (which is equivalent to that of the displacement, so in this case north).