Hello friends, I am very new to this forum and I´d like to consult you if i have any questions. Currently I am studying basic physics for my ug. I´d really apreciate it if you could help me out. 1. The problem statement, all variables and given/known data A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roon one second later. You may ignore air resistance. 2. Relevant equations a) If the height of the building is 20m, what must be the initial speed of the first ball if both hit the ground at the same time. b) Consider the same situation but now let the initial speed v0 be given and consider the height h of the building as the unknown. What must be the height of the building for both balls to reach the ground at the same time for each of the following value s of v0 (i) 6 m/s (ii) 9.5 m/s. 3. The attempt at a solution I was able to solve a) and i believe that the initail velocity must be 0.2 m/s. For the second question I have tried for hours but i cant seem to convince myself that this is possible at all. For instance if the ball 1 is in the air, 6 m, and the next second the second ball is dropped with the accelerration -g. How can the ball which has to travel the extra 6 m hit the ground at the same time ball 2 does? I am thoroughly confused. Please help me. THanks in advance.