A stone is DROPPED off a 144 foot cliff. A second later, another stone is THROWN off that cliff. The two hit the water at the same exact instant. What is the initial velocity of the second stone? The answer is 40 ft/second according to my book, but for some reason, I never get that. I set 4.9t^2 = v*(t-1) + 4.9(t-1)^2 I also set 144 = 4.9t^2 to get t = 5.421. I plug this back into the first equation, and my answer comes out to 10.908 ft/ sec! What am I doing wrong here?