During a vertical ascent, the propulsion system of an automated delivery drone is supplied with 12 400 J12\,400\text{ J}12400 J of total electrical energy from its onboard battery. The overall mechanical efficiency of the motor-propeller assembly during this phase is 42%.
Calculate the useful energy transferred to the drone as mechanical work.
Use the equation:
efficiency=useful energy transferredtotal energy supplied \text{efficiency} = \frac{\text{useful energy transferred}}{\text{total energy supplied}} efficiency=total energy supplieduseful energy transferred38 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.