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Topic 8: Energy - Forces doing work

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How efficient is a machine, and how can wasteful heating be reduced?

Efficiency of forces: calculating efficiency for a machine, why machines waste energy by heating, and reducing wasteful transfers by lubrication and streamlining.
A focused answer to Edexcel GCSE Physics 8.15 (and 8.10 to 8.11), covering the efficiency equation for a machine doing work, why mechanical processes waste energy as heat, and how lubrication and streamlining reduce wasteful energy transfers, with worked calculations.
9 min answer →

How does the energy of a system change when forces act, and how is energy dissipated?

Energy stores and system changes: the ways the energy of a system can change, energy transfers in a closed system, and how energy is dissipated when forces act.
A focused answer to Edexcel GCSE Physics 8.1 to 8.4 and 8.10 to 8.11, covering the ways the energy of a system can be changed, energy transfer diagrams, conservation of energy in a closed system, and how energy is dissipated and wasted as heating when forces do work.
9 min answer →

What is power, and how do you calculate it from energy or work and time?

Power: power as the rate of energy transfer or work done, the power equation, the watt as a joule per second, and the core practical measuring personal power.
A focused answer to Edexcel GCSE Physics 8.12 to 8.14, covering the definition of power as the rate of energy transfer or work done, the power equation, the watt as a joule per second, comparing devices by power, and the core practical measuring personal power, with worked calculations.
9 min answer →

What is work done, and how is it linked to energy transferred?

Work done and energy transfer: the work done equation, the link between work done and energy transferred, and how work done by friction raises temperature.
A focused answer to Edexcel GCSE Physics 8.5 to 8.7, covering the work done equation, the idea that work done by a force equals the energy transferred, the joule as a newton metre, and how work done against friction raises temperature, with worked calculations.
9 min answer →