Final answer:
The efficiency of the fan is 83.33%, which is calculated by dividing the kinetic energy output of 4000 J by the total energy input of 4800 J and then multiplying by 100%.
Step-by-step explanation:
To calculate the efficiency of the fan, we compare the kinetic energy output to the electrical energy input. Efficiency (η) can be calculated using the formula η = (useful energy output / total energy input) × 100%. In this case, the total energy input per minute is 4800 J, and the useful energy output (converted into kinetic energy of the fan) is 4000 J.
η = (4000 J / 4800 J) × 100% = (5/6) × 100% = 83.33%
Therefore, the efficiency of the fan is 83.33%, meaning that 83.33% of the electrical energy is transformed into kinetic energy, with the remainder presumably lost to heat and other forms of non-useful energy.