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state / describe / explain
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A wind-up toy car has a spring inside. You turn its key to wind the spring, put the car down and it whirrs across the floor, then slows down and stops. (a) State the store in which the energy is kept when the spring is wound up. (b) Describe how energy is transferred to the car’s kinetic store as it starts to move. (c) Explain why the car slows down and stops. State whether any energy has been destroyed.
state: give a concise answer. describe: give the features or what happens. explain: give reasons and connect them to evidence.
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Scope and sources
Cambridge IGCSE Physics 0625 · 2026–2028 v2 · Original learning materials.
Energy stores: kinetic, gravitational potential, chemical, elastic (strain), nuclear, electrostatic and internal (thermal) (1.7.1.1); transfers between stores by forces (mechanical work done), electrical currents (electrical work done), heating, and electromagnetic, sound and other waves (1.7.1.2); the principle of the conservation of energy, applied to simple examples including the interpretation of simple flow diagrams (1.7.1.3); Supplement: kinetic energy, Ek = ½mv² (1.7.1.4), change in gravitational potential energy, ΔEp = mgΔh (1.7.1.5), and the conservation of energy applied to complex examples, with Sankey diagrams (1.7.1.6); mechanical or electrical work done as energy transferred (1.7.2.1), W = Fd = ΔE (1.7.2.2); power as work done per unit time and energy transferred per unit time, P = W/t = ΔE/t (1.7.4.1). Energy resources and efficiency (1.7.3) are left to the next module, and electrical power (4.2.5) to the electricity modules.
Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.
Official Cambridge syllabus