A stone is thrown vertically downward from the edge of a cliff 45m high with an initial speed of 5m/s downward. Take g=9.8m/s2 and neglect air resistance.
a. (a) Calculate the time taken by the stone to reach the foot of the cliff.
b. (b) Determine the speed of the stone just before it strikes the ground.
c. (c) From what height (measured from the cliff top) should a stone be dropped from rest so that it reaches the ground with the same speed as in part (b)?