A stone A is dropped from rest from the edge of a cliff. Exactly 2.0s later, another stone B is projected vertically downward from the same point with an initial speed of 30m/s. Take g=10m/s2.
a. (a) Find the time, measured from the instant B is projected, after which B overtakes A.
b. (b) Calculate the speed common to both stones at the instant they meet.