While unrealistic, we will examine the forces on a legwhen one falls from a height by approximating the leg as a uniformcylinder of bone with a diameter of 2.3 cm andignoring any shear forces. Human bone can be compressed withapproximately 1.7 × 108 N/m2 beforebreaking. A man with a mass of 80 kg falls from aheight of 4 m. Assume his acceleration once he hitsthe ground is constant. For these calculations, g =10 m/s2.
What is his speed just before he hits theground?
With how much force can the \"leg\" be compressed beforebreaking?
If he lands \"stiff legged\" and his shoes only compress1Â cm, what is the magnitude of the average force heexperiences as he slows to a rest?
If he bends his legs as he lands, he can increase thedistance over which he slows down to 50 cm. Whatwould be the average force he experiences in thisscenario?
Dyne is also a unit of force and 1 Dyn =10−5 N. What is the maximum a bone can be compressedin Dyn/cm2?
