A ball is thrown vertically upward with an initial speed of 20 m/s. Two seconds later, a stone is thrown vertically (from the same initial height as the ball) with an initial speed of 24 m/s. At what height above the release point will the ball and stone pass each other?
1) 17 m
2) 21 m
3) 18 m
4) 27 m
5) 31 m
Answer: 1