An iron robot falls from rest at a great height. neglecting air resistance, what is its speed after it has fallen for 3.5 seconds? 13.3 m/s 9.8 m/s 34.3 m/s 9.8 m/s2

In an uniformly accelerated motion, the velocity of the object follows the law:

where  is the initial velocity, a the acceleration and t the time.

In our problem, the robot starts from rest, so the initial speed is zero: . The robot is in free fall, so the acceleraion is the gravitational acceleration . therefore, after a time , the velocity is