The object is in free fall, so its velocity follows the law:
[tex]v(t) = v_0 + gt[/tex]
where
[tex]v_0[/tex] is the initial velocity (zero)
g is the gravitational acceleration
t is the time
Since the initial velocity is zero, the velocity after t=30 s is
[tex]v(30 s)=gt=(9.81 m/s^2)(30 s)=294.3 m/s[/tex]
