Somehow two students managed to open two windows at the library. Student A is 17 m above the ground and Student B is 23.5 m above the ground. At the same time that Student A drops a ball, Student B throws a ball straight down at an initial speed of 7.36 m/s.

Question

At what height above the ground will Student B's ball catch up and pass Student A's ball?
At that moment, what is the difference in speed of the two balls?

Below answer with the height above the ground.

Answer 1

at time t they will be at the same height, when

17-4.9t^2 = 23.5-7.36t-4.9t^2
use that t to get the height

since gravity affects both balls equally, their speed difference is constant.