Calculate the energy stored (in joules) in our pendulum
Here are the measurements for the pendulum David, Xuedi and I did (from a great drawing of David):
1 pound * 9.8 / s / s * (24 inch) = 2.70979711 joules
2.7 joules/10sec = 0.27098 watts
Out pendulum worked for 2 minutes, so:
2.71 joules/120sec = 0.2258 watts.
Measuring the voltage of a stepper motor using an Oscilloscope
This DC motor has a voltage of around 3V.
Kinetic powered circuit
Rios and I built a weird thing that uses wheels to power 2 LEDs. 
We used two DC motors of this type:
