Start here · Essential guide
Understanding Forces and Newtons Laws of Motion
A plain-language tour of forces and the three laws of motion, with everyday examples of inertia, acceleration and action-reaction pairs, and where the laws stop working.
Universe and Matter
Forces, Energy and Motion
Classical physics that explains everyday motion, heat, sound and electricity.
Heat, Temperature and the Idea of Absolute Zero
Heat and temperature are not the same thing. Learn how they differ, how heat flows, and why absolute zero is the coldest temperature that can exist but never be reached.
How Electricity Works in Simple Terms
A beginner-friendly explanation of electric charge, current, voltage, resistance and circuits, using a water analogy and a simple worked example you can follow.
How Gravity Works from Newton to Einstein
Follow the idea of gravity from Newton's force acting at a distance to Einstein's curved spacetime, and see what each picture explains and where open questions remain.
How Nuclear Energy Is Released
An outline of how nuclear fission and nuclear fusion release energy from atomic nuclei, how the two processes differ, and why fusion power remains a research goal.
Magnetism and Why Compasses Point North
How magnetic fields work, why Earth behaves like a giant magnet, and why a compass needle swings toward the north, including the quirks of magnetic versus true north.
What Is Energy and Why Is It Conserved?
Energy is the capacity to cause change. Learn the main forms of energy, how it transforms, why the total stays constant, and what 'lost' energy really means.
What Sound Is and How It Travels
Sound is a vibration that travels through matter. Learn how pitch and volume work, how fast sound moves, and why it cannot travel through the vacuum of space.
Why Some Objects Float and Others Sink
Floating comes down to density and the upward buoyant force of a fluid. See how Archimedes' principle explains why steel ships float while small stones sink.
Why the Speed of Light Is a Universal Limit
Why relativity says nothing with mass can reach the speed of light, what the limit does and does not mean, and how it has been tested, explained without heavy math.
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Our Universe Space, the solar system and how we picture the cosmos. Physics and Matter Modern physics, light, the elements and everyday math. Stars and Galaxies How stars live and die and how galaxies and the early universe are understood. Planets and Space Exploration Missions, the Moon, eclipses and the search for life beyond Earth. Chemistry and Materials Reactions, everyday substances and how common materials are made.