Specifically, the boundary conditions may be, for instance, the position and velocity of {HEAD ~ the center} of {TAIL ~ gravity} at the start point, and the velocity of the center of gravity at the end point 
Specifically , the boundary conditions may be , for instance , the position and velocity of { HEAD ~ the center } of { TAIL ~ gravity } at the start point , and the velocity of the center of gravity at the end point
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH