Center of Mass
12
Center of Mass Chapter 12 KINE 3301 Biomechanics of Human Movement
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KINE 3301 Biomechanics of Human Movement. Center of Mass. Chapter 12. Segmental Method for Computing Center of Mass. SegmentSegment Weight (N )CM Location (%) Proximal End Head 0.032 x BW + 18.70 66.3 Top of Head Trunk 0.532 x BW – 6.93 52.2 1 ST Cervical - PowerPoint PPT Presentation
Transcript of Center of Mass
Center of Mass
Chapter 12
KINE 3301Biomechanics of Human Movement
Segmental Method for Computing Center of Mass
Segment Segment Weight (N) CM Location (%) Proximal End Head 0.032 x BW + 18.7066.3 Top of HeadTrunk 0.532 x BW – 6.93 52.2 1ST CervicalUpper Arm 0.022 x BW + 4.76 50.7 ShoulderForearm 0.013 x BW + 2.41 41.7 ElbowHand 0.005 x BW + 0.75 51.1 WristThigh 0.127 x BW – 14.8239.8 HipLower Leg 0.044 x BW – 1.75 41.3 KneeFoot 0.009 x BW + 2.48 40.0 Ankle
From: Chandler, R. F., C. E. Clauser, et al. (1975).
Computing the Location of a Segments CM
How to Use Segmental Method
1. Determine the X, Y location of the endpoints of all body segments.
2. Determine the weight of each segment.3. Determine the location of each segments center of mass.4. 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.
𝑥𝐶𝑀=𝑚1𝑥1+𝑚2𝑥2+𝑚3 𝑥3…
𝑚1+𝑚2+𝑚3…
𝑦𝐶𝑀=𝑚1 𝑦1+𝑚2 𝑦2+𝑚3 𝑦…
𝑚1+𝑚2+𝑚2…
Using Excel to Compute CM
Sagittal View Example
Segment Segment Weight (N) CM Location (%) Proximal End Head 0.032 x BW + 18.70 66.3 Top of HeadTrunk 0.532 x BW – 6.93 52.2 1ST CervicalThigh 0.127 x BW – 14.82 39.8 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)
