1. The problem statement, all variables and given/known data In my lab, we are studying the efficiency of a simple DC motor. In order to do this, we related the initial potential energy of the capacitor to the final potential energy of a mass (which remained constant for all three capacitors) that the motor lifted. I was instructed that the motor should have a constant efficiency even when it is powered using different capacitors with a capacitance of 0.21 F, 0.11 F, and 0.068 F respectively, however, in our experiment we found that the efficiency of the motor increased as the capacitor and I am having trouble explaining this. Furthermore, in trying to determine potential sources of error I was curious if the charge of the battery could have an effect on these calculations. 2. Relevant equations η= (mgh)/(.5CV^2) 3. The attempt at a solution I haven't been able to find much information regarding why the efficiency of the motor was experimentally determined to be different using different capacitors expect for that capacitors discharge much faster than batteries so I would assume that an increased capacitance would result in a faster discharge which could generate more torque on the motor and a high torque results in a higher efficiency. I'm not sure if this train of thought is correct but I think I am on the right track... Additionally, I wasn't sure if it would have in impact on the efficiency but I thought that using an old (not fully charged) battery may have an effect on its ability to fully charge the capacitor which could contribute to additional sources of error.