AQA GCSE Combined Science: Trilogy · 6.1

Energy

50 revision questions with answers for 6.1 Energy in AQA GCSE Combined Science: Trilogy (spec 8464). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below. Not official AQA material.

All 50 questions and answers

Question 1 · Spec 6.1.1.1
What is a system in physics?
Answer:
An object or group of objects being considered.
Question 2 · Spec 6.1.1.1
Name eight energy stores.
Answer:
Kinetic, thermal, chemical, gravitational potential, elastic potential, magnetic, electrostatic and nuclear.
Question 3 · Spec 6.1.1.1
Name four pathways by which energy can be transferred.
Answer:
Mechanically, electrically, by heating and by radiation.
Question 4 · Spec 6.1.2.1
What happens to total energy in a closed system?
Answer:
It remains constant; energy can be transferred between stores but cannot be created or destroyed.
Question 5 · Spec 6.1.1.1
Describe energy changes as a ball rises after being thrown.
Answer:
Its kinetic store decreases and its gravitational potential store increases; air resistance also transfers energy to thermal stores.
Question 6 · Spec 6.1.1.1
What happens to energy when a moving car brakes?
Answer:
Energy from the car's kinetic store is transferred mainly to thermal stores of the brakes and surroundings.
Question 7 · Spec 6.1.1.1
Describe the main useful energy transfer in an electric kettle.
Answer:
Energy is transferred electrically from the supply to the thermal store of the water.
Question 8 · Spec 6.1.1.2
State the kinetic energy equation and units.
Answer:
Ek = 0.5mv²; energy in joules, mass in kilograms and speed in metres per second.
Question 9 · Spec 6.1.1.2
Find kinetic energy for a 2.0 kg object moving at 3.0 m/s.
Answer:
Ek = 0.5 × 2.0 × 3.0² = 9.0 J.
Question 10 · Spec 6.1.1.2
How does doubling speed affect kinetic energy at fixed mass?
Answer:
Kinetic energy becomes four times as large because it is proportional to speed squared.
Question 11 · Spec 6.1.1.2
State the gravitational potential energy change equation.
Answer:
Ep = mgh; mass in kg, gravitational field strength in N/kg and vertical height change in m.
Question 12 · Spec 6.1.1.2
A 5.0 kg object rises 2.0 m. Use g = 9.8 N/kg to find its energy gain.
Answer:
Ep = 5.0 × 9.8 × 2.0 = 98 J.
Question 13 · Spec 6.1.1.2
State the elastic potential energy equation for a spring within its elastic limit.
Answer:
Ee = 0.5ke²; spring constant k in N/m and extension e in m.
Question 14 · Spec 6.1.1.2
Find energy stored by a 200 N/m spring stretched 0.10 m.
Answer:
Ee = 0.5 × 200 × 0.10² = 1.0 J.
Question 15 · Spec 6.1.1.3
What is specific heat capacity?
Answer:
The energy needed to raise the temperature of 1 kg of a substance by 1 °C.
Question 16 · Spec 6.1.1.3
State the equation linking heating energy and temperature rise.
Answer:
Change in thermal energy = mc x temperature change; c is in J/(kg °C).
Question 17 · Spec 6.1.1.3
Heat 0.50 kg of water by 10 °C. Use c = 4,200 J/(kg °C). Find energy.
Answer:
Energy = 0.50 × 4,200 × 10 = 21,000 J.
Question 18 · Spec 6.1.1.3 · Required practical
Outline a specific heat capacity investigation using a metal block.
Answer:
Measure mass and initial temperature; heat with an electric heater for a measured energy input; record temperature rise and calculate c = E/(m x rise).
Question 19 · Spec 6.1.1.3 · Required practical
How can the electrical energy supplied to a heater be determined?
Answer:
Use a joulemeter, or calculate E = Pt from heater power and heating time.
Question 20 · Spec 6.1.1.3 · Required practical
Why insulate the block and ensure good heater contact?
Answer:
Insulation reduces energy loss; good contact helps transfer energy into the block rather than the surrounding air.
Question 21 · Spec 6.1.1.3 · Required practical
How does unaccounted energy loss affect calculated specific heat capacity?
Answer:
The measured temperature rise is too small for the recorded input, so c = E/(m x rise) is overestimated.
Question 22 · Spec 6.1.1.4
What is power?
Answer:
The rate of energy transfer or the rate of doing work.
Question 23 · Spec 6.1.1.4
State two power equations.
Answer:
P = E/t and P = W/t; power in watts, energy or work in joules and time in seconds.
Question 24 · Spec 6.1.1.4
A motor transfers 3,600 J in 12 s. Calculate power.
Answer:
P = 3,600 / 12 = 300 W.
Question 25 · Spec 6.1.1.4
Two motors do equal work, but one takes half the time. Compare their powers.
Answer:
The faster motor has twice the power.
Question 26 · Spec 6.1.2.1
What does energy dissipation mean?
Answer:
Energy spreads into less useful stores, usually thermal stores of the surroundings, making it harder to use.
Question 27 · Spec 6.1.2.1
Why is 'energy is lost' an incomplete description of friction?
Answer:
Energy is conserved; friction transfers energy to thermal stores, where it becomes less useful for the intended purpose.
Question 28 · Spec 6.1.2.1
How can lubrication reduce unwanted energy transfers?
Answer:
It reduces friction between moving surfaces, so less energy is transferred by unwanted heating.
Question 29 · Spec 6.1.2.1
What is thermal conductivity?
Answer:
A measure of how readily energy is transferred through a material by conduction; higher conductivity means faster transfer under comparable conditions.
Question 30 · Spec 6.1.2.1
Why are low-conductivity materials useful for insulation?
Answer:
They reduce the rate of energy transfer through walls or other surfaces.
Question 31 · Spec 6.1.2.1
How does increasing insulation thickness usually affect cooling?
Answer:
It reduces the rate of energy transfer, so the object or building cools more slowly.
Question 32 · Spec 6.1.2.2
State the efficiency equations.
Answer:
Efficiency = useful output energy / total input energy, or useful output power / total input power.
Question 33 · Spec 6.1.2.2
An appliance gives 180 J useful output from 300 J input. Find efficiency.
Answer:
Efficiency = 180 / 300 = 0.60 = 60%.
Question 34 · Spec 6.1.2.2
A motor takes 800 W and provides 600 W useful power. Find efficiency.
Answer:
Efficiency = 600 / 800 = 0.75 = 75%.
Question 35 · Spec 6.1.2.2 · Higher only
How can an intended energy transfer be made more efficient?
Answer:
Reduce unwanted transfers, for example by reducing friction in machinery or insulating a hot system.
Question 36 · Spec 6.1.3
What is a renewable energy resource?
Answer:
One that is replenished, or can be replenished, as it is used.
Question 37 · Spec 6.1.3
Name the main non-renewable energy resources.
Answer:
Coal, oil, natural gas and nuclear fuels.
Question 38 · Spec 6.1.3
Name five renewable energy resources.
Answer:
Wind, sunlight, hydroelectricity, tides and waves; geothermal energy and biofuels are also examples.
Question 39 · Spec 6.1.3
What makes an energy resource reliable for electricity supply?
Answer:
Its output can be predicted or controlled sufficiently to help meet demand when needed.
Question 40 · Spec 6.1.3
Why are wind and solar output variable?
Answer:
Wind speed and sunlight vary with weather; solar output also varies with time of day and season.
Question 41 · Spec 6.1.3
How does tidal power differ from wind in predictability?
Answer:
Tides follow predictable cycles, although tidal generation is not continuous; wind is less predictable.
Question 42 · Spec 6.1.3
Why can reservoir hydroelectricity help meet changing demand?
Answer:
Stored water can be released quickly to drive generators when demand rises.
Question 43 · Spec 6.1.3
What is the energy source for geothermal power or heating?
Answer:
Energy transferred from hot rocks within the Earth.
Question 44 · Spec 6.1.3
Why is a biofuel renewable only if its source is replaced?
Answer:
New biomass must grow to replace what is harvested; unsustainable harvesting can deplete the resource.
Question 45 · Spec 6.1.3
Give two environmental disadvantages of fossil fuels.
Answer:
Carbon dioxide emissions contribute to climate change; other pollutants and extraction can harm health and ecosystems.
Question 46 · Spec 6.1.3
Give one benefit and one limitation of nuclear electricity generation.
Answer:
It has low operational carbon dioxide emissions, but produces radioactive waste and uses finite fuel.
Question 47 · Spec 6.1.3
Why are liquid fuels widely used for transport?
Answer:
They store substantial energy in a manageable volume and can be carried and supplied conveniently.
Question 48 · Spec 6.1.3
Why does electricity supply need to respond to demand changes?
Answer:
Consumers' energy use changes through the day and year, so supply must match the changing electrical demand.
Question 49 · Spec 6.1.3
Why may a technically suitable renewable project still be rejected?
Answer:
Cost, location, visual impact, habitat effects or public preferences can outweigh its benefits in a particular case.
Question 50 · Spec 6.1.3
What should a recommendation about an energy resource consider?
Answer:
Demand, reliability, cost, available sites, resource limits and environmental impacts, supported by the supplied evidence.

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