need help with this phys problem...Please help me out!?

Question

Let's say that a runner whose mass is 50kg stumbles and falls on her extended arm. If the arm's bones absorb all of the kinetic energy (disregarding the energy of the fall), determine the mininum velocity of the runner in which would make the arm bone break. Lets say the arm is 1m long and that the straight section area of the bone is 4cm^2.

The runner has healthy bones.
Please help out! there must be a way to answer this. thanks!!

Answer 1

Force is the d(mv)/dt that is rate of change of mass times velocity. Ordinarily when people fall the joints bend and slow down the momentum change, so the force is too small to damage bones. When the joints are locked in place and there is enough force, then it is the the "impact" points (where bones meet) that fracture which is the wrist, elbow or the ball joint of the shoulder. Falling from a standing position provides enough force to cause a fracture for most adults, no running is necessary.

Answer 2

Give me the resilience of a healthy bone and I might be able to help you.