Definition
Conservation Laws state that certain physical properties of an isolated system do not change over time, regardless of the internal interactions within the system.
Why It Matters
They provide the ultimate ‘reality check’ for any physical process, proving that energy and momentum can never be created from nothing.
Core Concepts
- Conservation of Energy: Energy cannot be created or destroyed. It may be transformed from one form to another (e.g., PE to KE), but the total amount remains constant.
- Conservation of Momentum: In the absence of an external force, the momentum of a system remains unchanged.
- How to read: “The net momentum before equals the net momentum after.”
- Meaning: Total vector momentum of an isolated system is invariant across any internal interaction (collision, explosion).
- Collisions:
- Elastic Collision: Objects rebound without lasting deformation or heat generation. Both momentum and KE are conserved.
- Inelastic Collision: Objects become distorted or generate heat. Momentum is conserved, but some KE is transformed into internal/heat energy.