the humerus can be approximated as a $33$cm long hollow cylinder with outer radius $1\mathrm{.}05$cm and inner radius $0\mathrm{.}43$cm$,$ suppose a gymnast whose arm bone has these dimensions does a one$-$arm handstand. excluding the arm, the mass of the gymnast is $68$kg$.$ a$)$what is the effective surface area of bone over which the weight acts? b$)$ what is the compressional strain of the humerus? c$)$ how much is the humerus compressed?