Conservation of energy

Science

Definition

The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another or transferred between objects. The total energy of an isolated system remains constant.

Examples

  • A roller coaster converts potential energy at the top of a hill into kinetic energy as it descends
  • When you rub your hands together, kinetic energy is converted into thermal energy through friction
  • In a light bulb, electrical energy is converted to light and heat energy
Key Fact

Total energy before = Total energy after; KE₁ + PE₁ = KE₂ + PE₂ (in the absence of non-conservative forces).

Related Terms

Kinetic energy Potential energy Work-energy theorem Energy conservation

Study This Concept

Practice conservation of energy with free review games in these units:

AP Physics 1 Unit 3: Work Energy and Power Physics Unit 3: Work and Energy