SIFT Mechanical Comprehension Practice Test

The conservation of energy equation states that the total energy in a closed system remains constant, which means that energy can neither be created nor destroyed but can only be transformed from one form to another. The correct expression, which reflects this principle, shows that the total energy (E_total) of a system is equal to the sum of its kinetic energy (E_kinetic) and potential energy (E_potential).

This equation illustrates how energy in a mechanical system is distributed. Kinetic energy is the energy of motion, while potential energy is the stored energy based on an object’s position or configuration. For example, when an object falls, potential energy is converted into kinetic energy as its speed increases.

This relationship ensures that as one form of energy decreases, another form compensates so that the total energy remains the same, embodying the conservation of energy principle. The other options suggest incorrect mathematical relationships that do not accurately represent how energy conservation operates in a physical system.