Human bones remain elastic if strain is less than 0.5%. However, the young’s modulus for compression `(Y_(c))` and stretch `(Y_(s))` are different. The typical values are `Y_(c) = 9.4 xx 10^(9) Pa` and `Y_(s) = 16 xx 10^(9) Pa`. The shear modulus of elasticity for the bone is `h = 10^(10) Pa` Answer following questions with regard to a leg bone of length `20 cm` and cross sectional area `3 cm^(2)` (a) Calculate the maximum stretching force that the bone can sustain and still remain elastic. (b) A man of mass 60 kg jumps from a height of 10 m on a concrete floor. Half his momentum is absorbed by the impact of the floor on the particular bone we are talking about. The impact lasts for 0.02 s. Will the compressive stress exceed the elastic limit? (c) How much shearing force will be needed to break the bone if breaking strain is `5^(@)C`.

Human bones remain elastic if strain is less than 0.5%. However, the y

1.	Human bones remain elastic if strain is less than 0.5%. However, the young’s modulus for compression `(Y_(c))` and stretch `(Y_(s))` are different. The typical values are `Y_(c) = 9.4 xx 10^(9) Pa` and `Y_(s) = 16 xx 10^(9) Pa`. The shear modulus of elasticity for the bone is `h = 10^(10) Pa` Answer following questions with regard to a leg bone of length `20 cm` and cross sectional area `3 cm^(2)` (a) Calculate the maximum stretching force that the bone can sustain and still remain elastic. (b) A man of mass 60 kg jumps from a height of 10 m on a concrete floor. Half his momentum is absorbed by the impact of the floor on the particular bone we are talking about. The impact lasts for 0.02 s. Will the compressive stress exceed the elastic limit? (c) How much shearing force will be needed to break the bone if breaking strain is `5^(@)C`.
Answer» Correct Answer - (a) `2.4 xx 10^(4)N` , (b) Yes , (c) `2.6 xx 10^(5) N`

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