a ball is dropped from rest at a height of 80 m above the ground. what is the speed just as it hits the ground?

Δx=Vi(t)+.5at²Δx=80a=9.8Vi=0 since its from rest, the initial velocity is 0.80=0+.5(9.8)t²t=16.33You can use one of the big five equations: Vf=Vi+atVf=0+9.8(16.33)Vf=160.034 m/s