Energy Stores & Transfers
Name one energy store.
Chemical / kinetic / thermal / gravitational potential / elastic potential / nuclear / magnetic / electrostatic.
What is conduction?
Transfer of heat through a solid by vibrating particles.
What is a renewable resource?
A resource that will not run out.
What is power measured in?
Watts (W).
What gas is most abundant in Earth’s atmosphere?
Nitrogen.
What is the unit of energy?
Joules (J).
Where does heat energy move from and to?
From hot to cold areas.
Name the 3 fossil fuels.
Coal / oil / natural gas.
Write the equation linking energy, power and time.
Energy = Power × Time.
What process removes CO₂ from the atmosphere?
Photosynthesis or dissolving
State the main law about energy
Energy cannot be created or destroyed, only transferred (conservation of energy).
Which states of matter can convection occur in and what do we call these states?
Liquids and gases (fluids)
What is released when fossil fuels are burned?
Carbon dioxide.
A 10 W device transfers 200 J. How long does it run?
20 seconds.
Name the 3 greenhouse gases.
Carbon dioxide / methane / water vapour.
Give one energy pathway.
Heating / radiation / mechanical work / electrical transfer.
Why do heated fluids rise in convection?
They become less dense as particles spread out.
Describe how a fossil fuel power station generates electricity.
Chemical energy → thermal energy (steam) → kinetic energy (turbine) → electrical energy.
A device uses 500 J and produces 400 J useful energy. Efficiency?
80%.
Why are black surfaces good absorbers of radiation?
They absorb infrared radiation effectively.
Describe an energy transfer in a wind turbine.
Kinetic energy of wind → kinetic energy of blades → electrical energy.
Why are metals good thermal conductors?
They have free electrons that transfer energy quickly.
Carbon dioxide, helium, krypton, methane, hydrogen
A device uses 2.4 kW of power for 3.5 hours. Calculate the total energy transferred with the correct units and explain what this value represents.
Energy (kWh) = Power (kW) × Time (hours) 2.4×3.5=8.4kWh This means the device has used 8.4 kilowatt-hours of energy, which is the total amount of electrical energy consumed over the 3.5 hours.
Describe how carbon from the atmosphere could end up going back into the atmosphere by combustion thousands of years later?
Carbon enters plants → buried as fossil fuels → burned by combustion → released back into the atmosphere as CO₂