A tower crane, lifting a load, performs 66 kJ useful work in 1 minute.
| September 25, 2021 | education
A tower crane, lifting a load, performs 66 kJ useful work in 1 minute. Determine the efficiency of the crane if the current in the 220 V electric motor is 10 A.
Initial data: t (duration of the tower crane electric motor) = 1 min (60 s); Ap (useful work of a tower crane) = 66 kJ (66 * 10 ^ 3 J); U (voltage for which the electric motor is designed) = 220 V; I (current in the electric motor) = 10 A.
The efficiency of a tower crane can be calculated by the formula: η = Ap / Az = Ap / (U * I * t).
Calculation: η = 66 * 10 ^ 3 / (220 * 10 * 60) = 0.5 (50%).
Answer: The tower crane has an efficiency of 50%.
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