The work done in raising it from the ground to that point against gravity.
Explanation
Gravitational Potential Energy is the energy possessed by an object by virtue of its position or configuration within a gravitational field.
- The work done in dropping it from that height. is incorrect: The work done in dropping an object represents the work done by the gravitational force as the object moves in the direction of the field. This process converts potential energy into kinetic energy but does not define the stored potential energy itself.
- The work done in raising it from the ground to that point against gravity. is correct: Gravitational potential energy is defined as the work done by an external agent in raising an object from a reference level (usually the ground, where potential energy is taken as zero) to a specific height against the force of gravity. Mathematically, near the Earth's surface, it is expressed as PE = mgh.
- The product of its mass and velocity. is incorrect: The product of mass and velocity (mv) defines momentum. Kinetic energy, which is energy of motion, is defined as ½mv².
- The force exerted by the object on the ground. is incorrect: The force exerted by the object on the ground corresponds to its weight (force), not its energy. Energy and force are distinct physical quantities with different dimensions.
Key Takeaway: Potential energy is the energy stored in a system due to the relative positions of its parts. It is quantitatively equal to the work done against a conservative force (like gravity) to achieve that position.