A woman with wieght 637N lies on a bed of nails. the bed has a weight of 735N and a lenght of 1.72m. the bed is held up by 2 supports, one ate the head and the other at the foot. Underneath each support is a scale. when the women lies in the bed, the scale at the foot reads 712N. how far is the center of gravity of the system from the foot of the bed of nails?