Question

A cannon ball launched horizontally with a speed of 20m/s and a baseball dropped off a cliff and it accelerates at a rate of 10m/s^2. Which will hit the ground first?

Answer 1

If they both start from the same height, then they both hit the ground at the
same time.  It makes no difference if their horizontal speeds aren't equal.
The cannon ball still accelerates downward at the same rate as the baseball.