Posted by qwertzuiop on .
You and your friend are leaning over the edge of the roof of a tall building. At the same instant you throw a baseball straight up with an initial speed vo and your friend throws a marble straight down with the same initial velocity vo. Assume that you can ignore air resistance. (1) Which object will reach the ground first, the baseball or the marble? (2) How will their speeds compare just before hitting the ground?
They both pass you at speed vo on the way down, but the baseball passes you later due to wasting time going up first.
Therefore the marble hits first.
Their motion is identical all the way down after passing you on the way down, same speed at every altitude.