Question

What is the final velocity of a 10 kg object that drops from rest and falls for 30 seconds?

Answer 1

The object is in free fall, so its velocity follows the law:
$v(t) = v_0 + gt$
where
$v_0$ 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
$v(30 s)=gt=(9.81 m/s^2)(30 s)=294.3 m/s$