What is the minimum speed of the runner that will cause a fracture of the arms?
Assume that a 50-kg runner trips and falls with his extended
hand into a wall (without
slowing down). If the bones of his two arms absorb all the
forward kinetic energy, what is the
minimum speed of the runner that will cause a fracture of the
arms? Assume that the length of
one arm is 1 m and that the area of each bone is 4 cm2
, on average.
aB = 16x107
Pa for the arm
a = F/A = (1.33 × 104
N) / (2.4 x 10^-4
m2
) = 5.5 x 107
Pa