Energy Stores (kinetic, gravitational, elastic, thermal, chemical, nuclear, electrostatic, magnetic)

OCR

GCSE

Energy is defined as the capacity to do work and is conserved within a closed system; it cannot be created or destroyed, only transferred between distinct stores. Candidates must identify specific stores (kinetic, gravitational potential, elastic potential, thermal, chemical, nuclear, electrostatic, magnetic) and analyze the pathways (mechanical, electrical, heating, radiation) by which energy shifts. Quantitative analysis involves calculating changes in energy using standard formulae for kinetic, gravitational, and elastic potential stores, linking these values to work done and power.

Objectives

Exam Tips

Pitfalls

Key Terms

Mark Points

What You Need to Demonstrate

Key skills and knowledge for this topic

Award 1 mark for correctly identifying the specific energy store involved (e.g., 'Chemical store' in a battery, not just 'battery energy').
Credit responses that explicitly state energy is 'transferred to the thermal store of the surroundings' when describing dissipation.
Award 1 mark for correct substitution of values into the kinetic energy equation (0.5 × m × v²) or gravitational potential energy equation (m × g × h) prior to calculation.
Candidates must link the decrease in one store (e.g., GPE) directly to the increase in another (e.g., Kinetic) when applying the Conservation of Energy.

Example Examiner Feedback

Real feedback patterns examiners use when marking

"You correctly identified the energy transfer, but you must specify the 'store' (e.g., 'thermal store') to gain the mark."
"Your calculation is correct, but you forgot to convert grams to kilograms. Always check your units first."
"Avoid saying energy is 'lost'. Instead, explain that it is 'dissipated to the surroundings'."
"Excellent application of the conservation principle. To improve, explicitly mention the transfer pathway (mechanical, electrical, heating, or radiation)."

Marking Points

Key points examiners look for in your answers

Award 1 mark for correctly identifying the specific energy store involved (e.g., 'Chemical store' in a battery, not just 'battery energy').
Credit responses that explicitly state energy is 'transferred to the thermal store of the surroundings' when describing dissipation.
Award 1 mark for correct substitution of values into the kinetic energy equation (0.5 × m × v²) or gravitational potential energy equation (m × g × h) prior to calculation.
Candidates must link the decrease in one store (e.g., GPE) directly to the increase in another (e.g., Kinetic) when applying the Conservation of Energy.

Examiner Tips

Expert advice for maximising your marks

💡When describing changes, use the sentence structure: 'Energy is transferred from the [X] store of the [object] to the [Y] store of the [object] via [pathway]'.
💡For Higher Tier calculations involving falling objects, remember that GPE lost = KE gained (assuming no air resistance) to solve for velocity.
💡Always check the prefix of units; kJ must be converted to J and kW to W before using them in equations.

Common Mistakes

Pitfalls to avoid in your exam answers

Stating that energy is 'lost', 'used up', or 'destroyed' rather than 'dissipated' or 'transferred to the thermal store'.
Confusing 'heat' (a transfer pathway) with 'thermal energy' (a store); OCR requires reference to the 'thermal store'.
Neglecting to square the velocity (v²) in kinetic energy calculations, or failing to convert mass from grams to kilograms.

Key Terminology

Essential terms to know

Conservation of energy in closed systems

Quantitative analysis of kinetic, gravitational, and elastic potential stores

Energy transfer pathways: mechanical, electrical, heating, and radiation

Dissipation of energy to thermal stores of surroundings

Calculation of efficiency and power

Likely Command Words

How questions on this topic are typically asked

Calculate

Describe

Explain

Suggest

Compare

Practical Links

Related required practicals

•{"code":"P1","title":"Specific Heat Capacity","relevance":"Investigating the thermal energy store of materials"}

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