$15.$ Three students $-$ Michael, Alia, and Matthew are standing on a roof that is $6\mathrm{.}0$ meters high.$$ Each person throws a ball with the velocity as illustrated.$$ initial velocity $=0$

Assuming that air resistance may be ignored, whose ball will hit the ground first?

$16.$Three students $-$ Michael, Alia, and Matthew are standing on a roof that is $6\mathrm{.}0$ meters high.$$ Each person throws a ball with the velocity as illustrated.$$ initial velocity $=0$

Assuming that air resistance may be ignored, whose ball will have the greatest speed the instant before they hit the ground?