What does this mean?: This tells us that this small electric motor at this voltage is 87.6% efficient at changing electric potential to mechanical motion. This is expected of an electric motor because they have so few moving parts and resistance.

Back to the main point: Does this mean the motor conserves energy? No, by the definition we used the power in did not equal power out therefore power was lost along the way from electric potential the mechanical movement. but if we had looked at the heat dissipated and the friction losses then by the definition of conservation of energy we would have a balanced system.

steps for improving this experiment:

1. put the whole system under vacuum to eliminate air resistance.
2. lubricate the motor to reduces the rolling resistance of the motor.
3. use a power source with data logging for both voltage and current.
4. use distance sensor and rotation sensor to more accurately determine speed and distance.
5. use a more precise scale.