Tag
Machines
Engines, gears, and mechanisms taken apart — 108 tiny stories across 6 shelves.
How things work
Everyday machines, taken apart — 78 stories.
All how things work →Throwing air downwards
Why Does a Wing Hold a Plane Up?
A wing throws air downward and the air shoves back. Lift grows with the square of speed, so twice as fast is four times as much of it.
Let’s go →A compass painted on the ground
Why Are Runways Numbered?
A runway's number is its compass heading divided by ten, so a pilot lining up can check the direction against the instruments.
Let’s go →Lighter than air, and too slow
Why Did Airships Stop Flying?
Airships float because their gas is lighter than air, but they were too slow and too big for weather, and aeroplanes overtook them.
Let’s go →And that is the boring half
Your Phone Beats the Computer That Flew to the Moon
The computer that landed Apollo 11 had less memory than one photo, and it was enough — because it did one job perfectly rather than everything adequately.
Let’s go →Wide, narrow, wide
How Does a Shop Scanner Read a Barcode?
Guard bars differ at each end, so a label scanned backwards still reads. The stripes carry no price at all — that lives in the shop's own computer.
Let’s go →Constant, invisible steering
Why Does a Moving Bike Stay Up?
The forks are angled so the front wheel trails behind the steering axis and turns into a fall by itself, curving the bike back upright.
Let’s go →Turning speed into heat
How Does Rubbing Stop a Car?
Brakes do not remove a car's energy, they convert it. Pads squeeze a spinning disc and all that movement leaves as heat the disc sheds into the air.
Let’s go →Two shapes that do not fold
Why Do Bridges Have Arches and Triangles?
Bridges use arches, triangles and cables because those shapes turn bending, which materials are bad at, into pushing or pulling, which they handle well.
Let’s go →A queue that eats itself
Why Do Buses Come in Threes?
Buses bunch because a late bus meets bigger queues and falls further behind, while the one behind it finds empty stops and catches it up.
Let’s go →Counting light in tiny buckets
How Does a Photo Get Caught?
A photo is a count of light: the lens focuses it, the shutter times it, and a grid of tiny wells measures how much landed in each one.
Let’s go →Raise the water, not the boat
How Does a Boat Go Uphill?
A lock does not lift a boat. It seals the boat into a chamber and changes the water level, so the boat simply keeps floating at a new height.
Let’s go →A shove converted to a spin
How Does a Bang Turn a Wheel?
Burning fuel shoves a piston down a tube, and a crankshaft bends that straight shove into the round motion the wheels actually need.
Let’s go →Electricity needs a full loop
Why Does a Switch Turn Things On?
Electricity only flows around an unbroken loop, so a few millimetres of air anywhere in that loop stops every last bit of it at once.
Let’s go →Something that always takes the same time
How Does a Clock Know When a Second Has Passed?
Every clock is built around one thing that repeats at an unchanging rate — a swinging weight, a quartz crystal — and a counter for the repeats.
Let’s go →Someone else's computer, in a shed
Where Is the Cloud?
The cloud is not in the sky. It is racks of computers in big cooled buildings, holding copies of your files and a vast electricity bill.
Let’s go →A desk and a filing cabinet
Where Does a Computer Keep Things?
A computer has two places to put things, and the difference is what happens at power-off: fast memory empties, slower storage does not.
Let’s go →Instructions, and nothing but
What Is a Computer Program?
A program is exact instructions run in order, with tests and repeats to change the path, followed by something that understands none of it.
Let’s go →A see-saw with a concrete end
Why Doesn't a Crane Tip Over?
A tower crane is a see-saw about its mast: a block of concrete on the short arm balances whatever hangs from the long one, distance included.
Let’s go →Rain, stored on a hillside
How Does a Dam Make Electricity?
A dam is a battery filled by the weather: it holds rain high up and lets it fall through a turbine, turning the height it loses into power.
Let’s go →Oil that refuses to be squashed
How Does a Digger Lift So Much?
Oil cannot be squashed, so pressure from a small piston reaches a much larger one, which pushes proportionally harder. That is the whole arm.
Let’s go →A circuit that completes itself
What Happens When You Press a Doorbell?
The button is not the bell. It is a gap in a circuit your finger closes, letting current turn a coil into a magnet that swings a hammer.
Let’s go →Only lifting the difference
Why Does a Lift Need a Counterweight?
A counterweight balances almost all of the car, so the motor only ever lifts the difference between the two — a small fraction of the whole load.
Let’s go →A relay, not a delivery
How Does an Email Find You?
An email is not carried to you. It is handed from server to server using the part after the @, and waits until your device asks for it.
Let’s go →Under the floor and back
Where Do Escalator Steps Go at the Top?
The steps never end. Two guide tracks at changing spacings make them form stairs in the middle and flatten at both ends, then return underneath.
Let’s go →Carrying heat out, not cold in
How Does a Box Make Itself Cold?
There is no such substance as cold. A fridge squeezes a gas hot to dump heat out behind it, then lets it expand cold to soak up some more.
Let’s go →Something has to break first
Why Do Fuses Blow?
A fuse is the weakest part of a circuit on purpose: a thin wire that melts before the cable behind it can ever get hot enough to burn.
Let’s go →A magnet, some wire, and movement
How Is Electricity Actually Made?
Every generator on Earth does one thing: it moves a magnet past coils of wire. Run the same machine backwards and it is a motor instead.
Let’s go →A fan and a hot wire, in that order
What Is Inside a Hairdryer?
A hairdryer is a fan and a coil of thin wire — and hair dries because moving air carries water away, not because the air is hot.
Let’s go →Adding a wave to its own mirror
Why Does Noise-Cancelling Work?
A predictable engine drone can be anticipated and cancelled, but clattering cutlery is different every time and mostly gets through regardless.
Let’s go →Stopping the cabin spinning
Why Does the Little Tail Rotor Matter?
Spinning the main blades twists the body the other way, so a small rotor on the tail pushes sideways to cancel the twist and hold the nose still.
Let’s go →Buying time, by millimetres
How Does a Helmet Protect a Head?
A helmet does not make your head harder. It crushes, which stretches a sudden stop over more time and cuts the force a brain must survive.
Let’s go →The same bag, holding less
Why Does Hot Air Lift a Balloon?
Heating the air drives some of it out of the open mouth, so what is left inside is about a fifth lighter than the air outside the balloon.
Let’s go →Somebody else's computer
Where Does a Website Actually Live?
A website is not in the air. It is files on a real machine somewhere, reaching you as small addressed packets handed from router to router.
Let’s go →Steam that flips a switch
Why Does a Kettle Switch Itself Off?
Steam runs down a hidden tube to a strip of two bonded metals, which bends as it warms until it snaps the power off behind your back.
Let’s go →A set of heights, not a shape
Why Does Only One Key Fit?
Every notch on a key lifts one spring-loaded pin to exactly the right height. Get all of them right at once and the barrel is finally free to turn.
Let’s go →Steel on steel, barely gripping
How Can One Engine Pull a Two-Kilometre Train?
Steel wheels on steel rails barely rub, so one engine can pull an enormous train — and barely grip, so it cannot stop quickly.
Let’s go →Lifting half the threads
How Does a Loom Turn Thread Into Cloth?
Weaving is not sewing: long threads are held tight, half of them lifted to open a gap, and a crossing thread is shot straight through it.
Let’s go →A speaker running backwards
How Does Your Voice Get Recorded?
A membrane thinner than paper flexes when your voice hits it, and that movement is measured thousands of times a second into a list of numbers.
Let’s go →Twisting water molecules
Why Does a Microwave Heat Food, Not the Plate?
A microwave flips a radio field billions of times a second and only water molecules follow, so wet food heats and a dry plate does not.
Let’s go →Splitting atoms to boil a kettle
How Does Nuclear Power Work?
A nuclear station is an ordinary steam power station with a very strange fire: split atoms make the heat, control rods hold the rate steady.
Let’s go →Dry heat, and a reaction
Why Does an Oven Brown Food?
Boiling water and an oven reach similar temperatures and only one makes toast, because dry heat lets the surface climb past a hundred degrees.
Let’s go →Sheets that slide off
Why Does a Pencil Leave a Mark?
The name comes from a 16th-century find people mistook for lead. More clay in the mix means fewer sheets come away, which is what makes a line fainter.
Let’s go →A hole, a lens and a very short while
How Does a Camera Freeze a Moment?
A photograph is light let in for a fraction of a second and recorded before anything in front of the lens had time to move and blur it.
Let’s go →Three pins, three different jobs
What Is Happening Inside a Plug?
A plug has several pins because electricity needs a way in, a way back, and an escape to the ground, plus a fuse designed to fail on purpose.
Let’s go →Pushed hard so less is lost
Why Are Power Lines So High Up?
Power lines carry electricity at enormous voltage because that wastes far less on the journey, then transformers step it back down.
Let’s go →Almost all of them boil water
How Does a Power Station Work?
Coal, gas and nuclear stations look nothing alike and all do one thing — boil water, so the steam spins a magnet inside coils of wire.
Let’s go →Dots, fired one at a time
How Does a Printer Place Ink So Exactly?
A resistor boils a speck of ink for a few millionths of a second and the steam bubble shoves one drop out. Black is added because three inks make mud.
Let’s go →A wing going round in circles
How Does a Propeller Pull a Plane?
A propeller blade is a wing bent into a circle. Instead of lifting upward it lifts forward, throwing air backward and never once stopping.
Let’s go →A wobble carried on a wave
How Does Music Get Into a Radio?
A station sends out one steady wave and wobbles it in time with the sound; your radio picks that wave alone and reads the wobble back off.
Let’s go →A light you cannot see
How Does a Remote Control Reach the Television?
Infrared will not pass through a sofa but bounces nicely off a pale ceiling, which is why aiming a remote at the wall so often works anyway.
Let’s go →Sense, decide, move
What Makes Something a Robot?
A washing machine follows instructions; a robot senses what is actually happening and decides what to do about it, many times a second.
Let’s go →Two pushes and a leftover
How Does a Boat Sail Into the Wind?
A sail turns wind into a mostly sideways push, the keel refuses to go sideways, and what is left over carries the boat forward, even upwind.
Let’s go →Two levers and a travelling point
Why Do Scissors Cut When One Blade Cannot?
One blade alone cannot cut, but two levers squeezing from opposite sides can — at a single point of contact that travels from pivot to tips.
Let’s go →One foot always down
Why Is a Scooter Easier Than a Bike?
A scooter is easier than a bicycle because you stand low with a foot free, so a wobble is corrected instead of becoming a fall.
Let’s go →A ramp wrapped round a stick
Why Is a Screw So Hard to Pull Out?
A screw is a ramp rolled into a spiral, turning many easy rotations into one enormous squeeze. Pulling it straight out fights the whole spiral at once.
Let’s go →Two threads that catch each other
How Does a Sewing Machine Stitch?
The needle never carries thread all the way through. It pushes a loop under the cloth, and a second hidden thread is hooked inside that loop.
Let’s go →A magnet shoving paper
How Does a Speaker Make Sound?
A coil carrying the recorded current becomes a magnet, dragging a paper cone in and out so it shoves the air at exactly that rhythm.
Let’s go →It falls there, mostly
How Does Water Climb to the Tap?
Water reaches your tap because it is stored higher than your house, and that height alone is what supplies the pressure inside the pipes.
Let’s go →Sound turned into electricity and back
How Does a Voice Travel Down a Wire?
A telephone turns the air's vibration into a matching electrical wobble, sends that down a wire, and turns it back into sound.
Let’s go →Mostly by not being sent
How Does a Picture Get to Your Television?
A moving picture is far too much to send, so almost all of it is thrown away: only what changed, and only what your eye would notice, makes the trip.
Let’s go →A switch that feels the room
How Does a Heater Know When to Stop?
A thermostat is just a switch that temperature opens and closes, which is why a room drifts slowly above and below the number you set.
Let’s go →A siphon, not a plug
Why Does a Toilet Flush by Itself?
A toilet flushes because a sudden rush of water fills the bend behind the bowl, and a full bend pulls the rest away by itself.
Let’s go →Grip, not speed
Why Do Tractors Have Huge Back Wheels?
A tractor is built to pull, not to travel: huge rear wheels give the grip that pulling needs and spread the weight so it does not sink.
Let’s go →A wave made of cars
Why Is There Nothing at the Front of a Traffic Jam?
Most traffic jams have nothing at the front: one small braking spreads backwards down the line as a wave and never quite fades out.
Let’s go →A wire loop under the tarmac
How Does the Road Know You Are Waiting?
The saw cuts in the road just before the stop line hold a loop of wire whose field changes when metal parks over it. A bicycle barely disturbs it.
Let’s go →Cones, not lips
Why Do Train Wheels Never Fall Off?
The inner lip hardly ever touches the rail. Leaning outward in a bend puts the outer wheel on a wider diameter, so it covers the extra distance itself.
Let’s go →Spreading the load
Why Do Trucks Have So Many Wheels?
Road damage depends on what each wheel presses down, not on the total, so a truck spreads thirty cars' worth of weight across many axles.
Let’s go →Not stronger. Just patient
How Does a Tiny Tugboat Move a Huge Ship?
A tug cannot outmuscle a container ship and does not have to: floating removes the weight, so a small push held for minutes moves anything.
Let’s go →Hold the roof up before you make it
How Do You Dig a Tunnel Without It Falling In?
The hard part is not removing the rock but stopping everything above from arriving in the hole, so the lining goes in as fast as the digging.
Let’s go →A very small parachute pointed the wrong way
Why Do Umbrellas Turn Inside Out?
An umbrella inverts because wind flowing over the dome lifts it from outside, and the ribs only brace against downward force.
Let’s go →The room does the pushing
Why Does Suction Pick Things Up?
Nothing sucks. The fan throws air out of the exhaust, the hose drops below room pressure, and the room's own air pours in carrying the dust.
Let’s go →Redrawn sixty times a second
How Does a Video Game Work?
A game is not a moving picture. It reads your controls, recalculates its whole world and draws a fresh still image sixty times a second.
Let’s go →Water carrying straight on
Why Does Spinning Get Clothes Dry?
A spin cycle throws nothing out. Water keeps travelling straight while the drum forces the clothes to curve away, so it leaves through the holes.
Let’s go →Pushed from below, never pulled
How Does Water Get Up to the Top Floor?
Nothing can suck water higher than about ten metres, so tall buildings push instead: a pump flings it out and a narrowing pipe presses it up.
Let’s go →One push, turned sideways
Why Does a Sharp Edge Cut So Easily?
A wedge redirects your downward push sideways and concentrates it onto almost no area at all, which is the whole of why a sharp edge cuts.
Let’s go →Three blades, and each one is a wing
How Does a Wind Turbine Work?
A turbine blade is not pushed by the wind, it is lifted sideways like a wing — and no turbine can take more than two-fifths of the wind's energy.
Let’s go →A clock that survives being carried
Why Can a Watch Work on a Moving Arm?
A watch replaces the pendulum with a wheel swinging against a fine spring, which does not care which way up it is or how much it is jolted.
Let’s go →A Y-channel and a wedge
What Actually Joins a Zip?
Nothing inside a zip's slider ever changes: a Y-channel hooks the teeth together one way and a wedge prises them apart when you pull the other.
Let’s go →Physics
Invisible forces you can play with — 13 stories.
All physics →Passing motion along
What Happens When Things Crash?
Motion is never destroyed in a crash, only handed over. What decides the damage is not the speed itself but how long the stop is allowed to take.
Let’s go →Bouncing all the way
How Does Light Go Round a Bend?
Light strikes the inside wall of a glass fibre so shallowly that it reflects perfectly, thousands of times a metre, tracing the cable round bends.
Let’s go →Why things stop
What Is Friction?
Every surface is rough close up. Friction is those roughnesses catching and grinding on each other, quietly turning motion into heat as they go.
Let’s go →Trading speed for strength
How Do Gears Work?
Count the teeth and you have the ratio. Ten driving thirty means three turns for one, and three times slower is three times the turning force.
Let’s go →You could not start, either
What If Friction Stopped for One Minute?
Everyone expects to slide. Almost nobody expects to be unable to start, hold, stand, or keep a single screw or knot from letting go.
Let’s go →Light marching in step
What Makes a Laser Different From a Torch?
A torch throws every colour every way with the waves unrelated. A laser is one colour, one direction, and every wave stepping in time.
Let’s go →Bending light on purpose
How Do Lenses Work?
Curved glass slows light by different amounts across a beam, and uneven slowing makes the beam turn — towards a point, or away from one.
Let’s go →Trading distance for force
How Do Levers Work?
A lever lets a small push move a big load, by making you push a long way to shift it a short one. Force and distance always trade off against each other.
Let’s go →Air shoved out of the way
How Does a Parachute Slow You Down?
A parachute does not slow you by being large. It forces you to shove a huge amount of air aside, and the air pushes back until it balances your weight.
Let’s go →Sharing the load
How Do Pulleys Help?
Run the rope through more pulleys and the load is shared across more sections, so each pull is lighter. You pay for it by pulling a great deal more rope.
Let’s go →The same climb, stretched out
Why Are Ramps Easier?
A ramp does not reduce the work of getting up there. It spreads the same climb over a longer walk, trading a hard short lift for an easy long push.
Let’s go →Storing a push
How Do Springs Work?
A spring stores the work you put into squashing or stretching it, then hands that energy straight back as it returns to its own shape.
Let’s go →Rolling beats dragging
Why Are Wheels So Good?
A wheel does not slide against the ground. Its contact patch sets down and lifts off again, which replaces sliding friction with very nearly none.
Let’s go →Everyday wonders
Kitchen, bubbles, echoes, and odd little magic — 8 stories.
All everyday wonders →A magnet inside a bigger magnet
How Does a Compass Work?
Earth is a giant magnet, and a compass needle is a small one pivoted loosely enough that it can swing round and line itself up with the field.
Let’s go →The string is the point
Why Does a Kite Stay Up on a String?
Cut the line and a kite drops rather than climbs, and on a still day you can fly one by walking backwards. A wing only needs air moving past it.
Let’s go →Iron, made temporarily magnetic
Why Do Magnets Stick to the Fridge?
A magnet lines up the tiny magnetic regions inside the door's steel, making the fridge briefly a magnet too. What you feel is two magnets attracting.
Let’s go →Waves that overlap themselves
Why Does a Microwave Heat Unevenly?
Microwaves bounce off the metal box and overlap each other, making fixed hot and cold bands. The turntable and standing time are there to even them out.
Let’s go →Eighty-eight little catapults
What Happens Inside a Piano?
A piano key does not push the hammer onto the string. It throws the hammer and lets go in mid-air, so the note is free to ring afterwards.
Let’s go →Making water boil hotter
How Does a Pressure Cooker Cook Faster?
Trapping the steam raises the pressure, and higher pressure pushes water's boiling point up to about 120 degrees. Hotter water simply cooks faster.
Let’s go →Thousands of tiny hooks
How Does Velcro Stick?
One side is thousands of stiff hooks, the other thousands of soft loops. Together they resist a flat pull hugely and give up at once to a peel.
Let’s go →Angled blades catching moving air
How Does a Windmill Turn?
Angled blades deflect moving air sideways and the air shoves back. The tip travels far faster than the root, so a blade is twisted along its length.
Let’s go →Space
Crashy night-sky stories — 7 stories.
All space →Leave most of the ship behind
How Did the Astronauts Get Back Off the Moon?
The bottom half kept the legs and the descent engine and simply stayed put. The cabin fired off it and only had to reach the ride waiting in orbit.
Let’s go →Pushing on nothing
How Do Rockets Launch?
A rocket flies by throwing hot gas downward very fast. The recoil from that throw is what lifts it, with nothing outside to push against.
Let’s go →Fast enough to miss
How Do Satellites Stay Up?
A satellite is not floating, it is falling — sideways, so fast that Earth keeps curving away underneath it before it can ever arrive.
Let’s go →A shell of debris
What Happens to Old Satellites?
Dead satellites and fragments keep orbiting for years, and at eight kilometres a second even a stray fleck of paint is dangerous.
Let’s go →Home at 28,000 km/h
Living on the Space Station
Sixteen sunrises a day, food that floats, and no such thing as a floor. Every ordinary habit has to be rebuilt for a place where nothing ever falls.
Let’s go →Working outside
What Is a Spacewalk Like?
Space offers nothing — no air, no warmth, no up. A spacewalk means wearing a personal spacecraft, tethered to the one you just climbed out of.
Let’s go →A bigger eye
How Do Telescopes Work?
A telescope is a bucket for light, and the wider the bucket the more it catches — far more starlight than a pupil a few millimetres across ever could.
Let’s go →Earth & sky
Weather, light, and the air around us — 1 story.
All earth & sky →Life & body
Seeds, hearts, senses, and growing things — 1 story.
All life & body →