A cordless hedge trimmer is supplied with 1.5 kJ of energy by its battery during a test. Of this energy, 540 J is dissipated by friction, electrical resistance and sound. The rest is transferred to the kinetic energy store of the blades.
Calculate the efficiency of the hedge trimmer as a percentage.
100 exam-style questions on Edexcel GCSE Physics 3.2 Dissipation and efficiency, covering 3.2.1 Dissipation of energy, 3.2.2 Reducing unwanted energy transfers, 3.2.3 Efficiency, and 3.2.4 Increasing efficiency. Each one has a worked solution and a mark scheme showing where the marks go.