Hey could plz provide a detailed explanation on how they got the answer a.) and c.)

5. Balls Off the Roof: A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roof a time t1 Ignore air resistance. a) If the height of the building is H , what must the initial speed of the rst ball be if both are to hit the ground at the same time? b) On a graph, sketch the positions of both balls as a function of time7 measured from when the rst ball is thrown. (3) Consider the same situation, but now let the initial speed v0 = UL of the rst ball be given and treat the height h of the building as an unknown a) There are several ways to reduce this but: 9 l2H H v0= t1+ g 9(9ti 2th1)2 c h: ) 8(UL gt1)2