AQA GCSE Physics (8463) · Paper 1

⚡ Energy

Revision notes written to the specification, with examiner tips and the required practicals. Every point here has flashcards in the Stickwise app.

Stores, transfers & equations

A system is any object, or group of objects, that you choose to study. Whenever something happens, energy is transferred from one store to another.

The kinetic energy store, for anything that is moving.
The gravitational potential energy store, for anything that has been raised up.
The elastic potential energy store, for anything that has been stretched or squashed.
The thermal energy store, for anything that is hot.
The chemical energy store, for fuel, food and batteries.
The nuclear energy store.
The magnetic energy store.
The electrostatic energy store.

Energy is transferred between stores in four ways: by mechanical work, when a force moves something; by electrical work, when a current flows; by heating; and by radiation, such as light or sound. For example, a falling ball transfers energy from its gravitational potential energy store to its kinetic energy store, and the brakes of a car transfer energy from the kinetic energy store to the thermal energy store through friction heating.

Kinetic energyThe kinetic energy store of a moving object is given by Ek = ½ m v², half of its mass multiplied by its speed squared. Doubling an object's speed multiplies its kinetic energy by four, which is one reason a small increase in speed makes a collision much more dangerous.

Gravitational PEThe gravitational potential energy store of a raised object is given by Ep = m g h, its mass multiplied by gravitational field strength (9.8 N/kg) multiplied by its height.

Elastic PEThe elastic potential energy store of a stretched or squashed spring is given by Ee = ½ k e², half of the spring constant multiplied by the extension squared, provided the spring has not been stretched beyond its limit of proportionality.

Specific heat capacityThe specific heat capacity of a material is the energy needed to raise the temperature of 1 kg of it by 1°C, given by ΔE = m c Δθ. Water has a very high specific heat capacity of 4200 J/kg°C, which is why it heats up slowly and stores thermal energy well.

power P = energy ÷ time — measured in watts (1 W = 1 joule per second)

🧪 Required practical: Measure the mass m of the metal block and the electrical energy E supplied to its heater. Record the temperature rise ΔT and calculate c = E/(m × ΔT). For a graph with temperature on the vertical axis and energy on the horizontal axis, gradient = 1/(m × c), so c = 1/(m × gradient). Insulate the block: energy lost to the surroundings makes this method overestimate c.

🎯 Examiner tip: Summer 2027: AQA gives you a clean copy of the physics equation sheet with every paper (separate Physics and Combined Science), so you do not have to memorise the equations on it. You still have to choose the right equation, rearrange it and use the right units. From 2028 the sheet is published by 1 September the year before, and questions will not be answerable just by copying from it.

Conservation & efficiency

The principle of conservation of energy states that energy can be transferred, stored or dissipated, but it can never be created or destroyed. Energy that is described as wasted has not vanished; it has spread out into the surroundings, usually as thermal energy, where it is no longer useful for the task at hand.

efficiency = useful output ÷ total input (multiply by 100 to get a percentage; efficiency can never be more than 100%)

Wasted energy can be reduced in several ways. Lubrication reduces friction between moving parts, and thermal insulation slows down how quickly a building cools by using thicker walls with low thermal conductivity. Materials that trap air, such as foam and fibreglass, are especially good at insulating in this way.

Energy resources

Renewable energy resources are replenished as they are used, and include wind, solar, hydroelectric, tidal, wave, geothermal and biofuel. Non-renewable resources will eventually run out; these are the three fossil fuels (coal, oil and gas) and nuclear fuel. All of these resources are used for transport, for heating, and for generating electricity.

Fossil fuels and nuclear power are reliable, since they can generate power on demand. However, fossil fuels release carbon dioxide (CO₂), which contributes to climate change, and sulfur dioxide (SO₂), which causes acid rain, while nuclear power leaves behind long-lived waste. Most renewable resources are clean but intermittent, since they generate no power when there is no wind or sun, and some flood valleys or spoil landscapes.

The switch to renewable energy has not happened everywhere because of several barriers: the cost of building new infrastructure, reliability gaps that mean backup capacity is still needed, and political and economic pressure to keep existing industries running. The scientific case for renewables is well established, but engineering and political factors remain the main obstacles to a faster transition.

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