Final answer:
Undeterminable elevator depth positions due to insufficient information; kinematics is the relevant concept in physics concerning the motion of objects.
Step-by-step explanation:
The question presented involves determining the positions of gold mine elevators after 18 seconds and gives us four scenarios: (a) an elevator accelerating upward, (b) an elevator accelerating downward, (c) an elevator moving upward with a constant velocity, and (d) an elevator moving downward with a constant velocity. To accurately determine which elevator is deeper, one would need additional information such as the initial positions, velocities, and the magnitudes of any accelerations of the elevators. Without this specific information, it's not possible to resolve the situation between the equipment elevator and miners' elevator. When an elevator is accelerating downward, as with the sensation described in the second question, passengers would feel lighter due to the reduced normal force acting upon them. The concept relevant to these discussion points is kinematics, which is a part of physics that deals with the motion of objects without considering the forces that cause the motion.