An electric motor has a total input energy of 850 J from the electrical supply.
It transfers 510 J of useful kinetic energy to a load.
What is the efficiency of the motor?
Use the equation: efficiency=useful output energy transfer÷total input energy transfer\text{efficiency} = \text{useful output energy transfer} \div \text{total input energy transfer}efficiency=useful output energy transfer÷total input energy transfer
0.400.400.40
0.600.600.60
0.850.850.85
1.671.671.67
37 exam-style questions on OCR GCSE Physics Power and efficiency. Each one has a worked solution and a mark scheme showing where the marks go.