The Fundamental Principle
Energy cannot be created or destroyed, only transformed from one form to another. This is the law of conservation of energy, one of the most important principles in physics.
Types of Energy
Kinetic Energy
Energy of motion. Formula: KE = ½mv²
A baseball flying through the air has kinetic energy.
Potential Energy
Stored energy due to position. Formula: PE = mgh
A rock at the top of a cliff has gravitational potential energy.
Roller Coaster Physics
At the top of a hill, the car has maximum potential energy and minimum kinetic energy. As it descends, potential energy converts to kinetic energy. At the bottom, kinetic energy is maximum and potential energy is minimum.
Energy at the Atomic Level
Even at the quantum level, energy conservation holds. When an electron jumps between energy levels in an atom, it either absorbs or emits a photon with exactly the right amount of energy to account for the difference.