Compute all parts of given problem:
Problem: A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roof 1.00 seconds later (ignore air resistance).
Part A: If the height of the building is 20.00 meters, what must be the initial speed of the first ball if both are to hit the ground at the same time?
Part B: Consider the same situation, but now let the initial speed of the first ball be given and treat the height of the building as an unknown. What would the height of the height of the building for both balls to reach the ground at the same time?
Please explain each step and equations used for above problem.