a) A stone is dropped from a height of 19.6 m above the ground, while a second stone is projected simultaneously from the ground with sufficient velocity to enable it to reach a height of 19.6 m. At what time and height will both stones be at the same level?
b) A boy throws a stone vertically downward with an initial speed of 12.0 m/s from the roof of a building, which is 30.0 m above the ground. (a) How long does the stone take to reach the ground? (b) What is the speed of the stone just before it reaches the ground?