Answer:
b) The isolated system stores 80 J of total energy, but it is converted to a different form of energy.
Explanation:
The Law of Conservation of Energy states that in an isolated system the total energy always remains constant. In our context this means that the box's energy cannot disappear from the isolated system of the box, slide, and the earth. Abiding the Law of Conservation of Energy, as the box slides down the friction-less table, its gravitational potential energy is converted into its kinetic energy.
Thus, in accord with the Law of Conservation of Energy, the energy of the system can neither decrease or increase, but is converted from one from to another. This rules of choices A, B, and C, leaving only choice B as correct.
