Determine how much compressive stress is present on the L1-L2 intervertebral disc

Figure 2 shows a lateral view of a normal spinal column.
a) Determine how much compressive stress is present on the L1-L2 intervertebral disc when a person weighing 63 kg stands in anatomical position. Assume that approximately 45 % of body weight is supported by this disc.
b) Determine the compressive stress on the L1-L2 intervertebral disc when the individual in a) stands upright holding a 25 kg suitcase.
For your calculations, assume that the disc is oriented horizontally and that is has a surface area of 20 cm2.

(Figure 2 Lateral view of a normal spinal column. The lumbar spine comprises the 5 vertebrae
that are below the thoracic vertebrae and are labelled L1, L2, L3, L4, and L5 in descending order
starting from the top. The intervertebral discs are numbered as well and are based upon the name of the
vertebrae above and below. The first lumbar disc is labelled L1-2, and they are labelled sequentially down to
L5-S1.)