I am having trouble with this one. for all the formulas I tried I need the velocity, which they don't tell us in the problem. Any help would be appreciated . A stone falls from rest from the top of a cliff. A second stone is thrown downward from the same height 2.4 s later with an initial speed of 47.04 m/s. They hit the ground at the same time. The acceleration of gravity is 9.8 m/s2 . How long does it take the first stone to hit the ground? Answer in units of s. How high is the cliff? Answer in units of m.