Energy — OCR GCSE Physics
In summary: Energy is a key topic in OCR GCSE Physics. Key exam tip: Always check that units are in SI (e.g., mass in kg, distance in m) before performing calculations.
Exam Tips for Energy
- Always check that units are in SI (e.g., mass in kg, distance in m) before performing calculations.
- When describing energy changes, clearly state the initial energy store and the final energy store.
- Remember that work done is only calculated using the distance moved in the direction of the force.
- Be prepared to use the law of conservation of energy to equate energy stores (e.g., GPE lost = KE gained).
- Ensure you can distinguish between power (rate of energy transfer) and energy (total amount transferred).
- Always show your working clearly when calculating efficiency.
- Remember that efficiency is a ratio and has no units.
- When explaining how to reduce energy waste, link your answer to specific methods like lubrication or insulation.
Common Mistakes
- Treating energy as a fuel-like substance that is 'used up' rather than transferred.
- Assuming resting objects have no energy.
- Believing that all energy transfers are 100% efficient.
- Confusing the concepts of force and energy.
- Failing to recognize that energy is dissipated into less useful stores rather than being truly 'lost'.
- Believing that energy can be 'used up' or destroyed rather than dissipated.
Marking Points
- Recognition that the total energy of a closed system remains constant (law of conservation of energy).
- Identification of energy stores and transfers in specific scenarios (e.g., objects projected upwards, moving objects hitting obstacles, electric kettles).
- Application of the work done formula: W = Fs (where s is distance along the line of action of the force).
- Calculation of energy changes using relevant equations for kinetic energy, gravitational potential energy, and elastic potential energy.
- Understanding of energy dissipation and the concept of useful vs. wasted energy.
- Use of kW h as a unit for electrical energy in domestic contexts.
- Definition of power as the rate of energy transfer.
- Calculation of efficiency using the ratio of useful output energy to total input energy.
← Back to Physics OCR GCSE Specification · All Physics Topics