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AQA GCSE Physics · Topic 4.1 Energy
Energy Stores and Systems
In this lesson you'll learn to: name the eight energy stores, describe how energy is
transferred between them when something changes, and write clear "store" sentences that say
which object, which store, and whether it increases or decreases.
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Prefer to watch? Scroll to the bottom for the video on this topic
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Start here — have a play
Don't read anything yet. Press the gold button and watch what happens to the coloured bars: one always goes down as another goes up, and the total never changes. Then switch on air resistance and see where the energy ends up.
Energy stores
Click a store to find out what it is.
Total energy in the system0.0 J
Watch this number. It never changes — energy is only transferred.
Tip: press the gold button, then watch one bar go down as another goes up.
Turn on air resistance to see where the energy ends up.
Say it like this
Press Push the ball ↑ to start.
Ball: mass 1 kg · g = 10 N/kg
▲ Watch the bars: for every bar that falls, another one rises by the same amount.
Seen what happens? Now learn how to say it.
Those coloured bars are the energy stores. The notes below name all eight of them, explain why the total never changes, and give you the exact sentence that earns the marks when the examiner asks you to describe a transfer.
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Revision notes
Energy is stored, not "used up"
Energy isn't a thing you can see or hold. It's a number we keep track of, and we say it is held in energy stores. Every object has energy in one or more stores.
When something happens — a ball falls, a kettle boils, a car brakes — energy is transferred from one store to another. Nothing is created and nothing disappears; the numbers just move between the stores.
⭐ Key fact — conservation of energy
Energy cannot be created or destroyed. It can only be transferred from one store to another, or from one object to another.
The 8 energy stores
You need to be able to name all eight. In exam questions, some come up again and again and some are rare — so learn them in this order.
The big two
In nearly every question🏃
Kinetic
The store of anything that is moving — a runner, a car, a falling ball, moving air.
Increases when the object speeds up · decreases when it slows down.⛰️
Gravitational potential (GPE)
The store of anything that has been lifted up — a book on a shelf, a skier at the top of a slope, water behind a dam.
Increases when the object is raised · decreases when it falls.Very common
Learn these next🪀
Elastic potential
The store of anything stretched or squashed — a spring, an elastic band, a bow, a trampoline, a compressed gas.
Increases as it is stretched/squashed · decreases as it springs back.🌡️
Thermal
The store of every object, linked to its temperature. This is the store energy usually ends up in when it is wasted.
Increases when the object gets hotter · decreases when it cools.Comes up regularly
Know what it is🔋
Chemical
The store inside food, fuels and batteries — anything that releases energy through a chemical reaction such as burning, respiring or discharging.
Decreases when fuel burns, food is respired or a battery runs down.Rarely used at GCSE
Just be able to name them🧲
Magnetic
Two magnets held apart, or pushed together against a repulsive force.
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Electrostatic
Charges held apart, or pushed together — like a charged balloon near a wall.
☢️
Nuclear
Energy stored in the nucleus of an atom, released in radioactive decay or nuclear fission.
💡 Exam tip — these are NOT stores
"Heat energy", "light energy", "sound energy" and "electrical energy" are not energy stores — they are ways of transferring energy (by heating, by waves, and electrically). Say "the thermal store increases", not "it turns into heat energy".
Systems and closed systems
A system is just the object, or group of objects, you have decided to look at. When a change happens, energy is transferred between the stores inside the system, and sometimes to objects outside it.
A closed system is one where no energy enters or leaves.
⭐ Key fact — closed systems
In a closed system, the total energy is constant. Energy can still move between the stores inside it, but the net change in the total energy of the system is always zero.
Where does "wasted" energy go?
Whenever there is friction, air resistance or something makes a sound, some energy is transferred to the thermal store of the surroundings. It is dissipated — spread out so thinly that it is no longer useful. It is never destroyed.
So never write "energy is lost". Write: "energy is dissipated to the thermal store of the surroundings."
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How to write it in the exam
Marks are given for naming the object, naming the store, and saying whether it increases or decreases. Use this sentence frame every single time:
The PWK sentence frame
The object's store
decreases, as the object's
store increases.
Some work is done against friction and the thermal store of the surroundings increases.
Some work is done against friction and the thermal store of the surroundings increases.
object — say whose store it is store — one of the 8 increases / decreases
A child slides down a slide
The child's gravitational potential store decreases, as the child's kinetic store increases. Some work is done against friction, and the thermal store of the slide and the air increases.
A ball is thrown straight up
The ball's kinetic store decreases, as the ball's gravitational potential store increases. Some work is done against air resistance, and the thermal store of the air increases.
An archer releases a bow
The bow's elastic potential store decreases, as the arrow's kinetic store increases.
A car brakes to a stop
The car's kinetic store decreases. Work is done against friction in the brakes, so the thermal store of the brakes and the surroundings increases.
A kettle boils water
The chemical store of the power station fuel decreases. Energy is transferred electrically to the kettle, and the thermal store of the water increases.
A bouncing ball that doesn't reach its original height
On impact the ball's kinetic store decreases as its elastic potential store increases. Not all of it is transferred back, because the thermal store of the ball and the ground increases — so the ball bounces lower each time.
💡 Exam tip — the three-part check
Before you move on, check every sentence has: 1) whose store it is, 2) which of the 8 stores, 3) increases or decreases. Miss one out and you miss the mark.
📘 Now do it in your workbook
Write your own store sentences for each scenario, then check them against the answers at the back of the book.
AQA GCSE Physics Workbook · ENERGY · pages 3 & 4Free sample = the two pages for this lesson. The full workbook covers the whole of Topic 1 Energy with exam-style questions and worked answers.
✅ Can you do it? Tick as you go
0% complete🎉 Nice work! You've ticked off every objective for this spec point.
Don't forget to hit “Mark complete” at the bottom of the lesson.
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Prefer to watch? Here's the whole thing
Everything above, explained out loud — useful for a last-minute recap, or if you'd rather hear it than read it.
▲ In GHL you can also use the lesson's built-in video field instead of this embed.
Now put it into practice
Watching is the easy bit — you only find out whether it's stuck by writing the sentences yourself. Pages 3 & 4 of the workbook are free, and the full book covers every spec point in Topic 1 Energy with worked answers.
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