When object reached the terminal speed then its acceleration is zero
So as per Newton's II law we can say
[tex]F_{net} = 0[/tex]
now in that case we can say that net force is zero so here weight of the object is counter balanced by the drag force when it will reach at terminal speed
so we can write
[tex]mg - F_d = 0[/tex]
so here we are given that
[tex]F_d = 30[/tex]
[tex]6*9.8 - 30*v = 0[/tex]
[tex]58.8 - 30 *v = 0[/tex]
[tex]v = \frac{58.8}{30} [/tex]
[tex]v = 1.96 m/s[/tex]
so terminal speed will be nearly 2 m/s