An object is projected with initial speed v0 from the edge of the roof of a building that has a height H. The initial velocity of the object makes an angle α0 with the horizontal. Neglect air resistance.

A) If α0 is 90∘so that the object is thrown straight up (but misses the roof on the way down), what is the speed v of the object just before it strikes the ground?

Express your answer in terms of some or all of the variables v0, H, and the acceleration due to gravity g.

B) If α0 = -90∘so that the object is thrown straight down, what is its speed just before it strikes the ground?