Final answer:
A pie chart includes both potential and kinetic energy to illustrate the transformation between these types of energy in a system where total energy is conserved.
Step-by-step explanation:
The pie chart shows both potential energy (PE) and kinetic energy (KE) because these are the two primary forms of mechanical energy in a system. In many physical systems, such as a pendulum, roller coaster, or a particle in a potential well, energy is conserved and constantly transformed between kinetic and potential forms. This can be observed in scenarios where the potential energy is maximal when an object is at its highest point as all energy is stored and the kinetic energy is zero.
Conversely, at the lowest point, the kinetic energy is maximal as all the stored energy has been converted into motion, and potential energy is at its minimum.
During such transformations, the total energy of the system remains constant, with changes in KE and PE illustrated by the pie chart. For example, at turning points in a potential energy diagram, the potential energy equals the total energy and the kinetic energy is zero. The chart or graph can visually demonstrate how these energies change in relation to one another due to conservation of energy principles.