help me physics
posted by william on .
The femur is a bone in the leg whose minium crosssectional area is about 3.60 E4 m2. A compressional force in excess of 6.90 E4 N will fracture this bone.
(a) Find the maximum stress that this bone can withstand.
1 N/m2
(b) What is the strain that exists under a maximumstress condition?

Stress, σ = force/area
=6.9E4/3.6E4 N/m²
=1.92E8 N/m²
Strain depends on the Young's modulus, E, of bone, which varies from 5 to 30 GPa for a calcium content of 250 mg/g. We will take tha average of 20 GPa.
strain, ε
= σ / E
= 1.92E8 Pa / 20 GPa
= 0.0096 (approx. 1%)
Reference for E:
http://jeb.biologists.org/cgi/reprint/202/18/2495.pdf