By what amount does the 52-cm-long femur of an 73 kg runner compress at this moment? The cross-section area of the bone of the femur can be taken as 5.2ร—10โˆ’4m2 and its Young's modulus is 1.6ร—1010N/m2.

Respuesta :

Answer:

4.55ร—10^-5m

Explanation:

Young modulus of the material is equal to the ratio of the tensile stress to tensile strain of the elastic material.

Young modulus = Tensile stress/Tensile strain

Tensile stress = Force/cross sectional area

Give mass = 73kg

Force = mg = 73ร—10 = 730N

Cross sectional area = 5.2ร—10^-4mยฒ

Tensile stress = 730/5.2ร—10^-4

Tensile stress = 1.4ร—10^6N/m

Strain = extension/original length

Given original length = 52cm = 0.52m

Tensile strain = extension(e)/0.52

Substituting the values given into the young modulus formula we have;

1.6ร—10^10 = 1.4ร—10^6/{e/0.52}

1.6ร—10^10 = 1.4ร—10^6ร—0.52/e

e = 1.4ร—10^6ร—0.52/1.6ร—10^10

e = 7.28ร—10^5/1.6ร—10^10

e = 4.55ร—10^-5m

This shows that the femur compresses by 4.55ร—10^-5m

The ground's normal on the femur while running can reach several larger

than when standing.

  • Amount of compression of the femur is approximately 1.343 ร— 10โปโด m.

Reasons:

The length of the bone, L = 52 cm = 0.52 m

Mass of the runner = 73 kg

Cross sectional area of the femur = 5.2 ร— 10โปโด mยฒ

Young's modulus = 1.6 ร— 10ยนโฐ N/mยฒ

Normal force = 3 ร— Body weight

Solution:

[tex]Young's \ modulus \ of \ elasticity = \dfrac{Stress}{Strain}[/tex]

[tex]Tensile \ stress \ on \ femur, \ \sigma = \dfrac{73 \times 9.81 \times 3}{5.2 \times 10^{-4} } \approx 4.132 \times 10^6[/tex]

[tex]Strain = \dfrac{Stress}{Young's \ modulus} \approx \dfrac{4.132 \times 10^6}{1.6 \times 10^{10}} \approx 2.582 \times 10^{-4}[/tex]

[tex]Strain = \dfrac{\Delta L}{L}[/tex]

Compression, ฮ”L = L ร— Strain

Therefore;

ฮ”L = 0.052 m ร— 2.582 ร— 10โปโด โ‰ˆ 1.343 ร— 10โปโด m

The compression of the femur when running, ฮ”L โ‰ˆ 1.343 ร— 10โปโด m.

Learn more ย here:

https://brainly.com/question/13257353

Question parameter obtained from a similar online question:

The normal force of the ground on the leg can be up to thrice the runners weight.