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Answer: CP BIO Stress on the Shin Bone. The compressive
Chapter 11, Problem 94P(choose chapter or problem)
Problem 94P
CP BIO Stress on the Shin Bone. The compressive strength of our bones is important in everyday life. Young’s modulus for bone is about 1.4 X 1010 Pa. Bone can take only about a 1.0% change in its length before fracturing. (a) What is the maximum force that can be applied to a bone whose minimum cross-sectional area is 3.0 cm2? (This is approximately the cross-sectional area of a tibia, or shin bone, at its narrowest point.) (b) Estimate the maximum height from which a 70-kg man could jump and not fracture his tibia. Take the time between when he first touches the floor and when he has stopped to be 0.030 s, and assume that the stress on his two legs is distributed equally.
Questions & Answers
QUESTION:
Problem 94P
CP BIO Stress on the Shin Bone. The compressive strength of our bones is important in everyday life. Young’s modulus for bone is about 1.4 X 1010 Pa. Bone can take only about a 1.0% change in its length before fracturing. (a) What is the maximum force that can be applied to a bone whose minimum cross-sectional area is 3.0 cm2? (This is approximately the cross-sectional area of a tibia, or shin bone, at its narrowest point.) (b) Estimate the maximum height from which a 70-kg man could jump and not fracture his tibia. Take the time between when he first touches the floor and when he has stopped to be 0.030 s, and assume that the stress on his two legs is distributed equally.
ANSWER:
Solution 944P
Step 1 :
Given
Youngs modulus of bone, y = 1.41010
Cross sectional area of bone, A =3cm = 310-4
Let l0 = the length of the bone
And Fmax = Maximum force that can applied to the bone before it fractured.
The bone can take 1% change in its length before fracturing.
= 1%of l0 = 0.01 l0