Question

The two thigh bones (femur bones) each of cross-sectional area `10 cm^(2)` support the upper part of a human body of mass 40 kg . Estimate the average pressure sustained by the femurs. `g=10m//s^(2)`

Answer 1

Total cross-sectional area of the femurs is `A=2xx10cm^(2)=20xx10^(-4)m^(2)`. The force acting on them is `F=40kg` wt=400N (taking `g=10ms^(-2)`). This force is acting vertically down and hence, normally on the femurs. Thus the average pressure is
`P_(av)=(F)/(A)=2xx10^(5)Nm^(-2)`