Key Concepts: Conservation of Energy

The Law of Conservation of Energy

Energy cannot be created or destroyed — it can only be transformed from one form to another or transferred between objects.

• Total energy of an isolated system remains constant.
• Energy forms include: kinetic, potential (gravitational, elastic, electric), thermal, chemical, nuclear, radiant.

Conservation of Mechanical Energy

• When only conservative forces (gravity, springs) act: KE₁ + PE₁ = KE₂ + PE₂.
• A pendulum swings back and forth converting KE ↔ PE continuously.
• A roller coaster: highest point = max PE, lowest point = max KE.

With Non-Conservative Forces

• Friction converts mechanical energy to thermal energy.
• Modified equation: KE₁ + PE₁ = KE₂ + PE₂ + W_friction.
• The total energy (all forms) is still conserved.