I have no clue what your computations are supposed to be doing.
Although you do not bother to define IROC, I figured it out.
Question: In your mind what does IROC represent, distance from some defined place, time since some defined time, or something else?
Does h(x) represent distance above the ground or below the ground?
If x represents time, time since when, the beginning of the universe, three minutes ago, when the object was launched?
What does positive velocity represent in terms of direction?
What does negative velocity represent in terms of direction?
When time is 29, what is the distance?
When time is 31, what is the distance?
So what in what direction is the object moving in the interval $29 < x < 31.?$