This type of coma is usually reversible once the blood sugar is corrected. Oxygen deprivation: Oxygen is essential for brain function. Cardiac arrest causes a sudden cutoff of blood flow and oxygen to the brain, called hypoxia or anoxia.
The external power supply is the AC power adapter that converts household AC electricity voltages to the much lower DC voltages needed to charge a mobile phone's internal battery.
Internal and external forces are cornerstones of Newtonian mechanics and the laws of motion. When a force is applied to a system, it is external if it causes the overall mechanical energy, made up of both kinetic and potential energy, to change by either losing or gaining energy. External forces are also known as nonconservative forces.