1. KINE 3301
Biomechanics of Human Movement
Center of Mass
Chapter 12

6. Segmental Method for Computing Center of Mass
Segment Segment Weight (N) CM Location (%) Proximal End
  Head x BW Top of Head
Trunk x BW – ST Cervical
Upper Arm x BW Shoulder
Forearm x BW Elbow
Hand x BW Wrist
Thigh x BW – Hip
Lower Leg x BW – Knee
Foot x BW Ankle
From: Chandler, R. F., C. E. Clauser, et al. (1975).

7. Computing the Location of a Segments CM

8. How to Use Segmental Method
Determine the X, Y location of the endpoints of all body segments.
Determine the weight of each segment.
Determine the location of each segments center of mass.
Multiply the segment weights by the x or y coordinates and then divide by the total weight to determine the location of the body center of mass.
𝑥 𝐶𝑀 = 𝑚 1 𝑥 1 + 𝑚 2 𝑥 2 + 𝑚 3 𝑥 3 … 𝑚 1 + 𝑚 𝑚 3 …
𝑦 𝐶𝑀 = 𝑚 1 𝑦 1 + 𝑚 2 𝑦 2 + 𝑚 3 𝑦… 𝑚 1 + 𝑚 𝑚 2 …

9. Using Excel to Compute CM

10. =2*((0.127*$L$2)-14.82) Sagittal View Example
Segment Segment Weight (N) CM Location (%) Proximal End
  Head x BW Top of Head
Trunk x BW – ST Cervical
Thigh x BW – Hip
In the back handspring assignment we are assuming that the right and left limbs move symmetrically, so the weights must be doubled, in cell F5 enter the following:
=2*((0.127*$L$2)-14.82)