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Energy and Power Study Cards
Free GCSE Physics Revision Flashcards
Cover energy stores, energy transfers, power, efficiency and the advantages of different energy sources with these free GCSE Physics flashcards. Includes the key equations and concepts.
Question
What are the main forms of energy?
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Answer
Kinetic, gravitational potential, elastic potential, chemical, thermal (heat), electrical, nuclear, sound, and light (electromagnetic).
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Question
What is the law of conservation of energy?
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Answer
Energy cannot be created or destroyed — it can only be transferred from one form to another. The total energy of a closed system remains constant.
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Question
What is work done?
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Answer
W = Fd, where F = force (N) and d = distance moved in the direction of the force (m). Work done = energy transferred. Unit: joule (J).
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Question
What is kinetic energy and its formula?
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Answer
Energy of a moving object. KE = ½mv², where m = mass (kg) and v = speed (m/s). Doubling speed quadruples kinetic energy.
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Question
What is gravitational potential energy (GPE) and its formula?
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Answer
Energy stored in an object due to its height above the ground. GPE = mgh, where m = mass (kg), g = gravitational field strength (9.81 m/s²), h = height (m).
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Question
What is power?
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Answer
The rate of energy transfer or the rate of work done. P = W/t = E/t. Unit: watt (W). 1 W = 1 J/s.
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Question
What is efficiency?
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Answer
Efficiency = (useful energy output / total energy input) × 100%. No machine is 100% efficient — energy is always lost, usually as heat or sound.
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Question
What is a Sankey diagram?
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Answer
A diagram showing energy transfers in a system — the width of arrows is proportional to the amount of energy. Useful energy is shown going forward; wasted energy (usually heat) branches off.
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Question
What is specific heat capacity?
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Answer
The energy needed to raise the temperature of 1 kg of a substance by 1°C. Q = mcΔT, where c = specific heat capacity, m = mass, ΔT = temperature change.
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Question
What is specific latent heat?
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Answer
The energy needed to change the state of 1 kg of a substance at constant temperature (without changing temperature). Q = mL. Latent heat of fusion (melting/freezing) and vaporisation (boiling/condensing).
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