In a uniformly accelerated motion, the velocity follows the law:
[tex]v(t) = v_0 + at[/tex]
where v(t) is the velocity at time t, v0 is the initial speed, a the acceleration.
In the free fall motion of the ball, the initial speed is [tex]v_0 = 3 m/s[/tex], while the acceleration is the gravitational acceleration: [tex]g=9.81 m/s^2[/tex]. We take downward as positive direction, so all the signs are positive (because both initial velocity and acceleration point downwards). Replacing t=2.0 s, we find the magnitude of the velocity at t=2.0 s:
[tex]v(2.0 s)=3.0 m/s + (9.81 m/s^2)(2.0 s)=22.6 m/s[/tex]
