The discussion clarifies that "change in energy" refers to the energy transferred to or from a system when work is done. Work is defined as the mechanical transfer of energy, which results in a change in the system's energy. Two primary types of mechanical energy are identified: potential energy and kinetic energy, with kinetic energy being the energy of motion. When a force is applied to an object, it accelerates, leading to a change in its kinetic energy, which work measures. Overall, work is expressed mathematically as the integral of the scalar product of force and distance covered.
