Energy Transfer and Conservation Revision Notes | GCSE AQA Higher Physics

What this lesson covers

Energy Transfer and Conservation: Explore the principles of energy conservation and transfer within closed systems.

• Explain the principle of energy conservation using examples from everyday situations
• Describe how energy is transferred between different stores in closed systems
• Calculate energy transfers using appropriate equations and units
• Evaluate the efficiency of energy transfers and identify wasted energy

Key ideas to keep in view

Use this lesson to stay inside Conservation and dissipation of energy while connecting the detail back to the wider Energy topic.

• Energy
• Conservation and dissipation of energy
• GCSE AQA Higher Physics

Revision notes

Read the core explanations from Energy Transfer and Conservation before testing yourself from memory.

1. Energy Never Disappears

When you drop a ball, where does its energy go? It doesn't vanish into thin air. This is one of the most fundamental rules in physics: energy cannot be created or destroyed; it can only move from one place to another or change from one form to another. In real-world systems, factors such as friction and air resistance transform energy into forms that are less useful for performing work.

Think of energy like money in a bank account: although you can move it between different stores (just like transferring funds between accounts), the total amount remains constant. This analogy is intended to provide a helpful starting point for understanding energy conservation, and as your studies progress, you'll explore the many ways energy can change form.

2. Energy Transfers in Closed Systems

A closed system is like a sealed box - nothing can get in or out. When we analyse energy in closed systems, we can track every joule of energy and see exactly where it goes.

Consider a bouncing ball in a sealed room. The ball starts with gravitational potential energy at the top. As it falls, this converts to kinetic energy. When it hits the floor, kinetic energy transfers to elastic potential energy as the ball compresses, then back to kinetic as it bounces up.

3. Energy Dissipation - The Wasted Energy Problem

Here's the catch: while energy is always conserved, it doesn't always stay useful. When you rub your hands together, kinetic energy transfers to thermal energy. The energy is still there, but it's spread out and much harder to use for doing work.

Every real energy transfer involves some dissipation. A car engine converts chemical energy from petrol into kinetic energy, but most of it dissipates as heat through the exhaust and radiator. The energy isn't lost - it's just no longer useful for moving the car.

4. Real-World Energy Systems

Let's apply these principles to systems you encounter every day. Understanding where energy goes helps us design more efficient machines and reduce waste.

5. Exam Technique - Energy Conservation Questions

Energy questions appear in every physics exam. The key is systematic thinking: identify the system, track the energy stores, and always check your answer makes sense.

Common exam mistakes include forgetting that energy is conserved (not lost), mixing up energy and power, and not identifying all the energy stores in a system. Practice identifying where energy goes in everyday situations.

Sources and content standards

Published by Revise Right. Use the official specification reference to check the requirements for your course. Content updated: 2026-03-20.

Continue through the topic

Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.