While unrealistic, we will examine the forces on a leg when one falls from a height...

While unrealistic, we will examine the forces on a leg when one falls from a height by approximating the leg as a uniform cylinder of bone with a diameter of 2.3 cm and ignoring any shear forces. Human bone can be compressed with approximately 1.7 × 108 N/m2 before breaking. A man with a mass of 80 kg falls from a height of 4 m. Assume his acceleration once he hits the ground is constant. For these calculations, g = 10 m/s2.

Part A

What is his speed just before he hits the ground?

Part B

With how much force can the "leg" be compressed before breaking?

Part C

If he lands "stiff legged" and his shoes only compress 1 cm, what is the magnitude of the average force he experiences as he slows to a rest?

Part D

If he bends his legs as he lands, he can increase the distance over which he slows down to 50 cm. What would be the average force he experiences in this scenario?

Part E

Dyne is also a unit of force and 1 Dyn = 10−5 N. What is the maximum a bone can be compressed in Dyn/cm2?

Expert Solution

genius_generous answered 9 months ago

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