|
Post by dubiousgolfer on Jan 28, 2022 13:32:22 GMT -5
My email to Dr Kwon about a physics issue concerning his website article- it has no real relevance to golf swing instruction but just seemed a bit strange why he should change the COR (centre of rotation) from the COM (Centre Of Mass) to the COP (Centre of Pressure). Dear Dr Kwon I was reading your website about 'Pivoting Moments' and wondering why you use the COP as the COR rather than the COM? His reply: The torque generated by the GRFs about the COM can be further broken down to 1. the torque generated by the combined GRF about the COM (i.e., the GRF torque), and 2. the torque generated by the GRFs about the COP (i.e., the pivoting torque). What you see here is the pivoting torque. The GRF torque on the horizontal plane is quite small and the majority is the pivoting torque. Cheers, Young-Hoo Kwon, Ph.D. Biomechanics & Motor Behavior Laboratory Texas Woman’s University P. O. Box 425647 Denton, TX 76204-5647, USA ------------------ My reply: Dear Dr Kwon Many thanks for your reply (although I am still having problems understanding). I thought that the combined GRF moment about the COM is being split into 3 components . 1. About the axis normal to the 'Frontal Plane' that passes through the COM 2. About the axis normal to the 'Sagittal Plane that passes through the COM 3. About the axis normal to the 'Transverse Plane' that passes through the COM Are you saying that the 'Pivoting Moment' about the COP are the components of point 3 but about an axis normal to the 'Transverse Plane ' that passes through the COP? DG PS. After reading some more about COP , I think the 'pivoting moment' about the COP is almost equivalent to the GRF moments about a vertical axis through the COM. Have therefore advised Dr Kwon to disregard my previous email.
|
|