An electric winch has an efficiency of 72% when lifting loads on a construction site.
The gravitational potential energy of a load increases by 1.8 × 105 J in a time of 30 s.
Calculate the total amount of energy supplied to the winch in the 30 s. Use the equation:
efficiency=useful output energy transfertotal input energy transfer \text{efficiency} = \frac{\text{useful output energy transfer}}{\text{total input energy transfer}} efficiency=total input energy transferuseful output energy transfer38 exam-style questions on Edexcel GCSE Physics 3.2 Dissipation and efficiency. Each one has a worked solution and a mark scheme showing where the marks go.