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Topic

Energy

Fuel, power, and where the go comes from — 52 tiny stories from every shelf.

The Sun is leaking

What Is the Solar Wind?

The solar wind is a steady stream of particles blowing out from the Sun.

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Not burning at all

What Is the Sun Burning?

The Sun is not burning: crushing pressure fuses hydrogen into helium and releases enormous energy.

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Passing motion along

What Happens When Things Crash?

In a collision, movement is passed between objects and never simply vanishes.

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Jostling passed along

Why Does a Metal Spoon Get Hot?

A metal spoon heats up because vibrating atoms pass their jostling along, and metals pass it exceptionally well.

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It never goes anywhere

Where Does Energy Go When Things Stop?

Energy never disappears when something stops; it has simply turned into heat, sound or something else.

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Everything is shaking

What Is Heat?

Heat is the movement of atoms — the faster they jiggle, the hotter it is.

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Nothing changes for free

Why Do Things Keep Moving?

Inertia is an object's refusal to change speed or direction on its own.

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It makes nothing — it slows

Does a Coat Make You Warm?

A coat does not warm you. It traps air and slows the escape of the heat your body already produces.

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Light marching in step

What Makes a Laser Different From a Torch?

A laser differs from a torch because its light is one colour, one direction, and every wave in step.

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Mass times speed

Why Are Heavy Things Hard to Stop?

Stopping something depends on both its mass and its speed, and spreading the stop over time reduces the force.

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Newton's third law

Every Push Has a Push Back

Forces always come in pairs — push anything and it pushes you back.

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Pushing in time

Why Does One Note Rattle the Window?

Resonance happens when a sound matches something's natural rhythm, so every wave adds to the last.

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Air, pushed

How Does Sound Travel?

Sound travels as a squeeze passed from air molecule to air molecule.

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Storing a push

How Do Springs Work?

A spring stores energy when squashed and gives it back when released.

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Light, cheap to reuse, and it protects itself

Why Are Drink Cans Made of Aluminium?

Aluminium is light, does not rust because it seals itself, and can be recycled with a fraction of the energy it took to make.

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Burning wood twice

Why Does Charcoal Burn Hotter Than Wood?

Charcoal is wood heated without air until only carbon is left, which then burns hotter and almost smokelessly.

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Loose electrons, and a price that works

Why Are Wires Made of Copper?

Copper carries electricity well because its outer electrons are loose, and it is cheap and bendy enough to use everywhere.

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Sunlight from a very long time ago

What Is Crude Oil?

Crude oil is ancient buried sea life, cooked under rock into a mixture that gets split into fuels and plastics.

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Millions of small links, joined into chains

What Is Plastic Actually Made Of?

Plastic is made of gigantic molecules — one small unit joined to itself thousands of times into a chain.

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Melting versus mashing

Why Does Glass Recycle Better Than Paper?

Glass and metal melt back to what they were. Paper fibres get shorter each time, so paper runs out of lives.

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The wick drinks its own fuel

Why Does a Candle Burn for Hours?

A candle burns steadily because the flame melts the wax and the wick draws exactly as much as it can burn.

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Glowing gas, not glowing wood

What Actually Is a Flame?

A flame is gas driven out of the fuel, glowing hot as it joins with oxygen from the air.

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Rock finally slipping

Why Does the Ground Shake?

Earthquakes happen when stuck slabs of rock suddenly slip past each other.

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A giant spark

What Is Lightning?

Lightning is a huge electric spark between a charged cloud and the ground.

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A wave that is all the way down

Why Are Tsunamis So Dangerous?

A tsunami is dangerous because it moves the whole ocean depth, not just the top.

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Energy moving, water staying

Do Waves Carry Water Along?

Ocean waves carry energy across the water while the water itself circles in place.

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Four things in a river

What Is Blood Made Of?

Blood is mostly water, carrying red cells, white cells and platelets around the body.

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Fetching oxygen, dumping waste

Why Do We Breathe?

We breathe to collect oxygen for burning food and to get rid of carbon dioxide.

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The colour it refuses

Why Are Leaves Green?

Leaves are green because chlorophyll absorbs red and blue and reflects green.

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Demand outrunning supply

Why Does Exercise Make You Puff?

You puff during exercise because muscles need far more oxygen than at rest.

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Energy passed along

Who Eats Whom?

A food chain follows energy from sunlight through plants and animals.

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Only ever pulling

How Do Muscles Move You?

Muscles move you by pulling, which is why they come in opposing pairs.

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Building food from air

How Do Plants Eat Light?

Plants use sunlight to build sugar out of air and water.

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Muscles working for the heat, not the movement

Why Do You Shiver When You Are Cold?

Shivering makes your muscles do pointless work on purpose, because most of what a muscle produces is heat.

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Taken apart, then absorbed

What Happens to Food You Eat?

Digestion breaks food into molecules small enough to enter your bloodstream.

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Getting your energy back

Why Does a Kangaroo Hop?

A kangaroo's tendons store and return energy like springs, so hopping costs it barely more at speed than at a crawl.

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Tangled chains straightening out

Why Do Rubber Bands Snap Back?

Rubber snaps back because stretching straightens its tangled molecule chains.

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Pushing in time

How Do You Make a Swing Go Higher?

Pumping works because small pushes timed to a swing's natural rhythm build up over many arcs.

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Angled blades catching moving air

How Does a Windmill Turn?

Windmills turn because angled blades deflect moving air and the air pushes back.

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A sealed tank of chemicals

Why Does a Battery Run Out?

A battery goes flat because it holds a fixed amount of reacting chemicals, and each electron spends some.

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A shove converted to a spin

How Does a Bang Turn a Wheel?

A car engine burns fuel to shove a piston, and a crankshaft converts that straight push into a spin.

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Someone else's computer, in a shed

Where Is the Cloud?

The cloud is racks of computers in big buildings, holding your files and sending them over the internet when you ask.

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Rain, stored on a hillside

How Does a Dam Make Electricity?

A dam holds water high up; letting it fall through a turbine turns the height it lost into electricity.

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Oil that refuses to be squashed

How Does a Digger Lift So Much?

A digger is strong because oil cannot be squashed, so a small piston pushing hard becomes a big piston pushing enormously.

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Only lifting the difference

Why Does a Lift Need a Counterweight?

A lift uses a counterweight so the motor only has to lift the difference, not the whole car.

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A magnet, some wire, and movement

How Is Electricity Actually Made?

A generator makes electricity by moving a magnet past coils of wire, which pushes the electrons in the wire along.

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Splitting atoms to boil a kettle

How Does Nuclear Power Work?

Nuclear power splits heavy atoms to release heat, which boils water and drives a turbine like any other station.

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Three pins, three different jobs

What Is Happening Inside a Plug?

A plug's pins give electricity a path in, a path back, and an emergency escape route to the ground.

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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.

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Almost all of them boil water

How Does a Power Station Work?

Most power stations burn or split something to boil water, and the steam spins a turbine that turns a generator.

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Light knocking electrons loose

How Does Sunlight Become Electricity?

A solar panel works because packets of light knock electrons loose and the cell's layers send them all the same way.

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Three blades, and each one is a wing

How Does a Wind Turbine Work?

A wind turbine's blades are wings: moving air lifts them sideways, spinning a shaft that turns a generator.

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