where: C= distance from the feet (axis of rotation) to a plane passing through the subject 8 COG F5: scale reading WB- weight of the reaction board Wg = weight of the subject Data Collection. We will now use this equation to determine your own center of gravity height by lying on the board with your feet at the end away from the scale. Measure the variables in the table below during two conditions: first with your arms at your side, and then again with both of your arms raised straight above your head and resting on the reaction board. 1. Mass of the reaction board: 52-8 kg 2. Length of reaction board: 2-2 m 3. Your body mass: 67'4 kg 4. Your height: 1 .73 m 5. Scale reading (board only): 26-4 kg 6. Scale reading ( your arms by sides): 48-2 kg 7. Scale reading (your arms overhead): 49-6 kg