引用:
原帖由 qwer 於 2016/1/20 12:04 AM 發表
R is compression force, why it's not 'compressing' the spine ?(ie why it's not pointing towards the spain?)
Actually R is just a reaction of the sum of the other forces. That piece of bone doesn't actively give the force. If the main part of the spine was not in touch of that piece of bone, the R would be zero.
So... you may think the horizontal component of R is to balance that of T. While the vertical component of R is to help that of T, because L + W seems quite large.