🔹 Conservation of Energy

The Law of Conservation of Energy says that energy cannot be created or destroyed, only transformed from one form to another. The total energy in a system always stays the same!

👉 Example: In a roller coaster 🎢, energy changes:

• At the top: Maximum Potential Energy (PE).

• Going down: PE converts into Kinetic Energy (KE) (motion).

• With friction: Some energy turns into heat & sound (but is not lost!).

  
  

🔹 Energy Efficiency

Energy efficiency means how much useful energy you get from a system compared to the total energy used. No machine is 100% efficient because some energy is lost as heat, sound, or friction.

👉 Example:

• LED bulbs 💡 → 80-90% efficient (most energy becomes light).

• Old light bulbs → Only ~10% efficient (most energy turns into heat).

  
  

🔹 Calculating Efficiency

Efficiency(%)=(Useful Energy Output / Total Energy Input)×100.

👉 Example:

• A car engine takes 100 J of fuel energy.

• It produces 30 J of useful movement energy.

• Efficiency = (30/100)×100=30%(30/100) \times 100 = 30\%(30/100)×100=30%

That means 70% of energy is lost as heat & sound! 🚗🔥