Final answer:
While laying on the ground, an individual has minimal potential energy due to the lack of height and zero kinetic energy due to the absence of motion, resulting in virtually no mechanical energy.
Step-by-step explanation:
When you are laying on the ground, your mechanical energy in terms of movement is essentially zero because you are not moving. Mechanical energy is a combination of kinetic energy, which is related to the motion of an object, and potential energy, which is stored energy based on an object's position or arrangement. For instance, when you lift a brick, your muscles provide the mechanical energy to move the brick. However, while stationary on the ground, your potential energy is at a minimum because you are not elevated above the ground, and your kinetic energy is zero because you are not in motion.
The Law of Conservation of Mechanical Energy states that if non-conservative forces like friction do not do work and there are no external forces, the mechanical energy remains constant. But, when lying still on the ground, the sum of kinetic and potential energy (mechanical energy) does not exist in a practical sense - it's as if the system's mechanical energy is 'unused' at this point. This illustrates how nonconservative forces, such as friction when a car stops, can dissipate kinetic energy into other forms, like heat, rather than conserving it within the system.