Question

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

Answer 1

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

`v(t) = v_0 + at`
where
`v_0` 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:
`v_i =0`. The robot is in free fall, so the acceleraion is the gravitational acceleration
`g=9.81 m/s^2`. therefore, after a time
`t=3.5 s`, the velocity is

`v(3.5 s)= 0 + (9.81 m/s^2)(3.5 s)=34.3 m/s`