The motion of the rock is a free-fall motion, which is a uniformly accelerated motion with constant acceleration [tex]g=9.8 m/s^2[/tex] downward, so the distance covered by the rock in a time t can be found by using the formula
[tex]S=\frac{1}{2} gt^2[/tex]
By substituting t=3 s into the formula, we find the distance the rock travels after falling for 3 seconds:
[tex]S=\frac{1}{2} (9.8 m/s^2)(3 s)^2=44.1 m[/tex]
