Bone has a Young's modulus of about
1.8 x 100 Pa. Under compression, it can
withstand a stress of about 1.59 x 108 Pa be-
fore breaking.
Assume that a femur (thigh bone) is 0.53 m
long, and calculate the amount of compression
this bone can withstand before breaking.
Answer in units of mm.

505.62 mm

Explanation:

Young's modulus of a material is given by,

Stress is the force experienced by the material per unit area (which is why stress has the same units as pressure).

Strain is the ratio between the change in length/area/volume to the original length/area/volume of the material (and hence a dimensionless quantity). Basically, it gives us a measure of the change in dimensions due to the stress experienced.

So, for the given problem,

or,      (since we need to find the compression of the bone at the critical stress point)

or,

not really sure but thinking 1.54 mm/us