1. The problem statement, all variables and given/known data A 45 kg object is lifted vertically at a constant speed to a height of 9.0m by a 750 W electric motor. If this motor is 25% efficient in converting electric energy to mechanical energy, how long does the motor take to lift the object? 2. Relevant equations 3. The attempt at a solution I have no idea how to even start this question. I dont understand why it is in electric circuit unit.