A particular electric car is supplied with 300 kJ of chemical energy by the battery. Of this, a total of 70.5 kJ of energy is wasted as heat.Calculate the overall efficiency of the electric car.Hint: First work out the useful output energy. You do not need to convert from kilojoules (kJ) to joules (J).

17 The total energy supplied to an electric motor is E. Energy Q is wasted and the remaining energydoes useful work.What is the efficiency of the motor?A QE B QE    – 1 C 1 – QE    D (1 )QE

A car is driven along a level road. The total energy is put from the petrol is 60 KJ and the car wastes 45KJ of energy. What is the efficiency of the car?

Petrol cars transform chemical energy into useful kinetic energy. A typical energy efficiency of this transformation is 15%.Compare the efficiency of the petrol car to the electric car described above.Hint: Use your answer from the previous question to answer this.

(e)     When the heater is supplied with 120 J of energy each second, the internal energy of theice increases by 45 J each second.Use the following equation to calculate the efficiency of the heater.

thermal power plant is generating power to supply loads through a transmission line. An electric motor is one of the loads. The efficiency of the thermal power plant is 60% and the power loss on the transmission line is 7%. If the motor’s efficiency is 95% and its output power is 100 kW, how much energy should be utilized by the power plant to feed the need of the motor for 5 hours? Choose the value that is the closest to the answer.