Study the scenario.

A box is initially at the top of a slide, storing 80 J of gravitational energy. The isolated system includes the box, slide and earth.

As the box slides down the frictionless slide, what happens to the total energy of the system?

a) The total energy of the system increases to more than 80 J of energy as it gains other forms of energy
b) The isolated system stores 80 J of total energy, but it is converted to a different form of energy.
c) The isolated system stores slightly less than 80 J of total energy, and it is converted to a different form of energy
d) The total energy of the isolated system decreases to 0 once the box reaches the bottom of the slide.

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.