A rock that is thrown vertically downward takes 0.85 s to reach the ground. If it travels 9.2 m before reaching the ground, what is its velocity when it strikes the ground?
9.2 + v0 t - 4.9t^2 = 0
where t = 0.85
v = v0 - 9.8t = (-9.2 + 4.9 * 0.85^2)/0.85 = -6.66 m/s