At a voltage of 220V, the current in the electric motor is 1.25A, the efficiency is 40%.

At a voltage of 220V, the current in the electric motor is 1.25A, the efficiency is 40%. What useful work does the electric motor do in 25 minutes?

To calculate the useful work of the electric motor used, we apply the formula: η = Ap / (U * I * t), whence Ap = U * I * t * η.
Values of variables: U – operating voltage on the electric motor (U = 220 V); I (current) = 1.25 A; t – operating time (t = 25 min, in SI t = 1500 s); η – efficiency (η = 40% = 0.4).
Calculation: Ap = U * I * t * η = 220 * 1.25 * 1500 * 0.4 = 165,000 J (165 kJ).
Answer: The useful work is 165 kJ.