Both kinetic and potential energy.
Explanation
The phenomenon is governed by the Law of Conservation of Mechanical Energy. For a freely falling object (ignoring air resistance), the total mechanical energy remains constant throughout the motion. This total energy is the sum of gravitational potential energy and kinetic energy.
Detailed Analysis
- At the initial height (Start): The object possesses maximum gravitational potential energy ($PE = mgh$) because of its position relative to the ground. Its velocity is zero, so its kinetic energy ($KE$) is zero.
- During the fall: As the object descends, its height decreases, reducing its potential energy. Simultaneously, gravity accelerates the object, increasing its velocity and thus its kinetic energy. The potential energy is continuously converted into kinetic energy.
- At the midpoint: The object is at half the initial height, meaning it still possesses potential energy ($PE = mg \frac{h}{2}$). Since it has been accelerating, it has acquired velocity, meaning it also possesses kinetic energy. Specifically, at the midpoint, half of the initial potential energy has been converted into kinetic energy.
- Just before impact: Potential energy becomes zero (at reference level), and kinetic energy becomes maximum.
Therefore, at any intermediate point, including the midpoint, the object possesses both forms of energy.
Key Takeaway: In a free-fall system, potential energy transforms into kinetic energy. At any point between the start and the ground, the object possesses a combination of both potential and kinetic energy.