(ii) Calculate the direction and magnitude of the joint force at the mid-point between the fourth and fifth lumbar vertebrae by considering the forces and moments acting on the lower body.
Direction of joint force at midpoint between L4 and L5 = F =?
ILB lower body mass moment arm = 15cm
WLB Lower body weight = 370N
Weight moment arm = IW = 35 cm
W uB upper body weight = 430 N
L uB Upper body mass moment arm =15 cm
LlB lower body mass moment arm=15cm
lw weight moment arm =35cm
muscle force moment arm =50mm
trunk angle 40 degree with the vertical