Answer:
C. The power of the motor is 40 W and the system is 20% efficient, so the time it takes for the motor to lift the load through 0.50 meters can be calculated using the following equation:
Time = (Load x Distance) / (Efficiency x Power)
Time = (40 N x 0.50 m) / (0.20 x 40 W)
Time = 50 seconds.