Question 1 Report
Fig. 1.1 shows the energy flow of an electric motor. It is supplied with 60 J of electrical energy and transfers 45 J as useful kinetic energy. State how much energy is wasted and its main form.
The correct answer is 15 J, mostly as thermal energy. By conservation of energy, wasted energy = input - useful output = \( 60 - 45 = 15 \, \text{J} \). In an electric motor, friction in the bearings and resistance in the coils dissipate the wasted energy mainly as thermal energy (heat). 105 J would exceed the input, and sound or chemical energy are not the main waste forms in a motor.
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