Physics / core

Energy

Also known as: E

definition

The capacity to do work or cause change in a physical system, measured in joules. Energy is the unifying concept across all of physics — every process involves energy transformation.

💡 Intuition

The 'currency' that makes things happen. It's what you need to move, heat, or change anything.

Core Idea

Energy can change forms but never disappears—it's conserved.

🔬 Example

A battery stores energy; a moving car has energy; hot coffee has energy.

🎯 Why It Matters

Energy is the unifying concept across all of physics — every process involves energy transformation.

⚠️ Common Confusion

Energy is not a substance you can touch—it's a calculated quantity that's conserved.

Related Concepts

How Energy Connects to Other Ideas

Once you have a solid grasp of energy, you can move on to kinetic energy, potential energy and work.

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Go Deeper

Frequently Asked Questions

What is Energy in Physics?

The capacity to do work or cause change in a physical system, measured in joules.

Why is Energy important?

Energy is the unifying concept across all of physics — every process involves energy transformation.

What do students usually get wrong about Energy?

Energy is not a substance you can touch—it's a calculated quantity that's conserved.

🧪 Visualization Static

Visual demonstration of this concept.