Energy > Forms, conservation of energy and energy transfer > Mechanical Energy
Mechanical energy is the sum of potential energy and kinetic energy (the two main forms of energy). When in an object act only conservative forces (e.g. gravity) its mechanical energy remains constant. Elastic collisions are examples where the mechanic energy of a system is conserved.
Connection to Big Idea about forces: The principle of the conservation of mechanical energy states that the total mechanical energy in a system remains constant as long as the only forces acting are conservative ones (e.g. gravity, electric force). Elastic collisions are an example where the mechanic energy is conserved.
Connection to Big Idea about the universe: Any object in motion has mechanical energy. For example, a planet’s orbit around a star is determined by its mechanical energy.
Connection to Big Idea about particles: Electrons have mechanical energy due to their orbits around the atomic nucleus. The electrons’ orbits are defined by the mechanical energy of the system.
Connection to Big Idea about quantum: Contrary to the prediction of classical electrodynamics, the existence of stable atoms according to Bohr’s theory are due to the presence of specific trajectories of orbiting electrons in which the mechanical energy of the system remains constant.
Subjects related: Chemistry, Physics
Age ranges: 12-13,13-14,14-15,15-16