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Topic 3: Conservation of energy

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What does conservation of energy mean, and how is energy dissipated?

Conservation and dissipation of energy: the principle of conservation of energy in a closed system, how energy is dissipated to less useful stores, and why mechanical processes waste energy by heating.
A focused answer to Edexcel GCSE Physics 3.4 and 3.6 to 3.8, covering the principle of conservation of energy, why the total energy in a closed system does not change, how energy is dissipated to less useful stores, and why mechanical processes waste energy by heating the surroundings.
9 min answer →

What is efficiency, and how do you calculate it for a device?

Efficiency: the meaning of efficiency, the efficiency equation as a ratio of useful to total energy (or power), and why no device is perfectly efficient.
A focused answer to Edexcel GCSE Physics 3.11, covering the meaning of efficiency, the efficiency equation in terms of useful and total energy transferred (and as a percentage), the power form of the equation, Sankey diagrams, and why no real device is 100% efficient, with worked calculations.
9 min answer →

What are the energy stores, and how do you draw an energy transfer diagram?

Energy stores and transfers: the named energy stores, the ways energy is transferred, and drawing and interpreting energy transfer diagrams for everyday systems.
A focused answer to Edexcel GCSE Physics 3.3 to 3.5, covering the named energy stores, the four pathways by which energy is transferred, drawing energy transfer diagrams, and analysing the energy changes when systems such as a falling object or a kettle change.
9 min answer →

How do you calculate gravitational potential energy and kinetic energy, and how do they interchange?

Gravitational and kinetic energy: the change in gravitational potential energy equation, the kinetic energy equation, and how energy transfers between the two stores.
A focused answer to Edexcel GCSE Physics 3.1 and 3.2, covering the change in gravitational potential energy equation, the kinetic energy equation, the units and what each symbol means, and how energy transfers between the gravitational and kinetic stores, with worked calculations.
9 min answer →

How can unwanted energy transfers be reduced, and what affects a building's rate of cooling?

Reducing unwanted energy transfer: lubrication and thermal insulation, and how the thickness and thermal conductivity of walls affect the rate of cooling of a building.
A focused answer to Edexcel GCSE Physics 3.9 and 3.10, covering ways of reducing unwanted energy transfer including lubrication and thermal insulation, and how the thickness and thermal conductivity of the walls of a building affect its rate of cooling.
9 min answer →