Blog topic
Physics articles
Circuits, why the sky is blue, waves, floating and sinking, mirrors and lenses, orbits, heat transfer, magnets, and the core quantities: momentum, kinetic and potential energy, friction, pressure, torque and projectile motion. Every piece leads with the everyday observation and only then brings in the formula.
45 explainers, newest first. Each one ends with real questions from the unit that teaches it, so you can read the explanation and then check whether it stuck.
These are the readable companion to the Physics track, which holds 18 units and 2,143 practice questions. If you are starting the subject rather than looking something up, the study guide is the better place to begin.
How Do X-Rays Work? Seeing Bones Through Skin
X-rays are light with enough energy to pass through flesh and be stopped by bone. How they are made, what the dose means, and how a CT scanner builds a slice.
September 15, 20265 min readHow Does a Compass Work? A Needle, the Earth's Core and a Pole That Wanders
A compass needle is a magnet that aligns with the Earth's field, made by molten iron flowing in the core. Why north is not quite north, and why the field flips.
September 15, 20264 min readHow Do Helicopters Fly? Rotors, Torque and Why They Are So Hard to Control
A helicopter's rotor is a spinning wing, and tilting it is how the aircraft moves. How lift, steering and the tail rotor work, and what if the engine fails.
September 15, 20265 min readHow Does a Bicycle Stay Upright? Gyroscopes, Trail and a Century of Wrong Answers
A moving bicycle balances itself, and for a century physicists gave the wrong reason. What the gyroscope does and does not do, what trail is, and the 2011 test.
September 15, 20265 min readHow Does a Parachute Work? Drag, Terminal Velocity and the Shape of a Canopy
A parachute slows a fall by dragging so much air that the body reaches the speed of a jog instead of a crash. The physics, and why canopies became wings.
September 15, 20265 min readHow Does a Vacuum Flask Keep Drinks Hot? Blocking Heat Three Ways at Once
A vacuum flask keeps coffee hot and lemonade cold by stopping the three ways heat travels. How it works, and who invented it.
September 15, 20264 min readHow Does a Microwave Oven Heat Food?
Microwaves twist water molecules billions of times a second. Why that heats food from within, why the plate stays cool, and why metal sparks.
September 14, 20265 min readWhat Is Resonance? Why a Push at the Right Moment Does So Much
Every object has frequencies it prefers to vibrate at. Push it at one and small efforts add up, which tunes radios, shatters glasses and wrecked a bridge.
September 14, 20265 min readWhy Is the Speed of Light the Universe's Speed Limit?
Nothing with mass can reach 300,000 kilometres a second, and the reason is not engineering. What Einstein showed about time, mass and energy.
September 14, 20265 min readHow Do Aeroplanes Fly? What Actually Holds a Wing Up
A wing stays up by pushing air down. Why the textbook explanation is wrong, what the angle of the wing does, and why a plane can fly upside down.
September 14, 20264 min readWhat Is Nuclear Fission? Splitting the Atom and What Comes Out
Fission is the splitting of a heavy nucleus into two lighter ones, releasing energy and neutrons that split more. How it was found, and how a reactor tames it.
September 14, 20265 min readHow Does a Laser Work? Light That Marches in Step
A laser makes light of one colour with every wave in step, by making excited atoms emit in unison between mirrors. The physics, and what the beam can do.
September 14, 20264 min readHow Do Rockets Work? Throwing Mass Backwards to Reach Orbit
A rocket moves by throwing its own mass out behind it at high speed. Why that is the only way to push in a vacuum, why most of it is fuel, and what orbit is.
September 14, 20265 min readWhy Ice Floats When Almost Nothing Else Does
Most solids sink in their own liquid. Ice floats because water molecules lock into an open lattice as they freeze, with effects from icebergs to burst pipes.
September 9, 20264 min readWhat Is Projectile Motion? A Simple Physics Guide
Learn how horizontal velocity, vertical acceleration, gravity, and launch angle combine to shape the path of a moving object.
August 17, 20266 min readWhat Is Work in Physics? Force, Distance, and Energy Transfer
Learn how force and displacement determine mechanical work, how to use the work formula, and why work is measured in joules.
August 17, 20265 min readWhat Is Centripetal Force? The Inward Force in Circular Motion
Learn why circular motion needs a net inward force, how speed and radius affect it, and which real forces can provide it.
August 17, 20265 min readWhat Is Angular Momentum? Rotation and Conservation Explained
Learn how mass, rotation, and distance from an axis affect angular momentum and why spinning systems can conserve it.
August 17, 20265 min readWhat Is Torque? How Force Makes Objects Rotate
Learn how force, distance from a pivot, and angle determine turning effect, and why torque matters in levers, tools, and rotation.
August 17, 20265 min readWhat Is Frequency in Physics? Waves, Cycles, and Hertz Explained
Learn what frequency in physics is, how hertz measures repeating cycles, how frequency relates to period, and why it matters for waves, sound, and light.
August 17, 20265 min readWhat Is Potential Energy? Stored Energy Explained Simply
Learn how position and arrangement can store energy, with clear examples from gravity, springs, and energy transfers.
August 14, 20265 min readWhat Is Acceleration? A Simple Physics Guide
Learn how velocity changes over time, why slowing down can still be acceleration, and how to read acceleration in simple examples.
August 14, 20265 min readWhat Is Friction? How Surfaces Resist Motion
Learn why surfaces resist sliding, how static and kinetic friction differ, and when friction helps or wastes useful energy.
August 14, 20265 min readOhm's Law: How Voltage, Current, and Resistance Connect
Ohm's law links voltage, current, and resistance in simple circuits. Learn the formula, rearrange it safely, and understand when the model applies.
August 14, 20266 min readSpeed vs Velocity: What Is the Difference in Physics?
Speed vs velocity is a key physics distinction. Learn how distance and displacement change the calculation, and why direction matters for velocity.
August 14, 20266 min readWhat Is Pressure in Physics? Force, Area, and Pascals Explained
Learn how force and area work together, why pressure changes, and how to solve simple pressure problems using pascals.
August 14, 20266 min readWhat Is Density in Physics? Mass, Volume, and the Density Formula
Learn how mass and volume combine in the density formula, how to compare materials, and how to handle common units.
August 14, 20266 min readWhat Is Momentum? A Simple Physics Explanation
Learn how mass and velocity combine to describe motion, how momentum changes with force, and why total momentum is conserved in interactions.
August 13, 20265 min readWhat Is Kinetic Energy? A Simple Physics Explanation
Learn how mass and speed affect the energy of motion, how to use the formula, and why doubling speed has a large effect.
August 13, 20265 min readHow Power and Efficiency Describe Energy Transfer
Power tells you how quickly energy is transferred, while efficiency compares useful output with total input. Together they help explain why devices doing the same job can behave very differently.
August 8, 20265 min readHow Electromagnetic Induction Generates Current
A changing magnetic field can create a potential difference in a conductor. This principle, called electromagnetic induction, is the basis of generators and many other electrical devices.
August 8, 20265 min readHow Terminal Velocity Is Reached
A falling object reaches terminal velocity when air resistance grows to balance its weight. Its speed then becomes constant because the resultant force has fallen to zero.
August 5, 20265 min readHow Springs Store and Release Energy
A spring changes shape when a force stretches or compresses it. Within its elastic range, the extension follows a simple pattern and energy is stored for later release.
August 5, 20265 min readHow Newton's Laws Explain Motion
Newton's three laws connect force, mass and motion. Together they explain why objects keep moving, accelerate under unbalanced forces and push back during every interaction.
August 4, 20266 min readHow Heat Travels by Conduction, Convection and Radiation
Thermal energy moves through conduction, convection and radiation. The three processes often work together, but each transfers energy in a different way.
July 29, 20265 min readHow Magnets Create Forces at a Distance
Magnets create fields that exert forces on other magnets and magnetic materials. Poles, field direction and moving electric charges help explain attraction, repulsion and electromagnets.
July 29, 20265 min readHow Levers and Pulleys Make Work Easier
Levers and pulleys change the size or direction of a force. They do not remove the need for work, but they can trade a smaller force for movement over a greater distance.
July 29, 20265 min readWhy Mirrors Reflect Images
A mirror forms an image because light reflects from its smooth surface in a predictable way. The image appears behind the mirror even though no light travels there.
July 26, 20265 min readHow Lenses Bend and Focus Light
Lenses form images by refracting light at curved surfaces. Their shape and the distance of an object determine whether an image is magnified, reduced, real or virtual.
July 26, 20265 min readWhy Satellites Stay in Orbit
A satellite remains in orbit because gravity pulls it inward while its sideways motion carries it forward. Orbit is a continuous fall around Earth rather than an escape from gravity.
July 26, 20265 min readHow a Simple Electric Circuit Works
A circuit needs a source, a complete path and components that use electrical energy. Once you can follow the loop, circuit diagrams become much less mysterious.
July 24, 20265 min readWhy the Sky Looks Blue and Sunsets Look Red
Sunlight contains many colours, and Earth's atmosphere scatters them unevenly. That one idea explains both the blue daytime sky and the warm colours near sunset.
July 24, 20265 min readHow Waves Carry Energy Without Carrying Matter Away
Waves transfer energy through repeating disturbances. From water ripples to sound and light, the material involved usually moves locally while the wave travels onward.
July 24, 20265 min readWhy Some Objects Float and Others Sink
Floating depends on density and the upward force created by displaced fluid. Shape matters because it changes how much water an object can push aside.
July 24, 20265 min readA Beginner's Guide to Physics
Physics is the rulebook for how things move and work. Start with forces and energy in everyday life, and understand the why before you ever meet a formula.
December 19, 20255 min read