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A gymnast does a one-arm handstand. The humerus, which is the upper arm bone between the elbow and the shoulder joint, may be approximated as a 0.26-m-long cylinder with an outer radius of 1.07 x 10-2 m and a hollow inner core with a radius of 3.7 x 10-3 m. Excluding the arm, the mass of the gymnast is 57 kg. Bone has a compressional Young's modulus of 9.4 x 109 N/m2. (a) What is the compressional strain of the humerus

Respuesta :

Answer:

0.00018784

Explanation:

[tex]L_0[/tex] = Initial length of cylinder = 0.26 m

[tex]\Delta L[/tex] = Change in length

[tex]r_o[/tex] = Outer radius = [tex]1.07\times 10^{-2}\ m[/tex]

[tex]r_i[/tex] = Inner radius = [tex]3.7\times 10^{-3}\ m[/tex]

m = Mass of arm = 57 kg

g = Acceleration due to gravity = 9.81 m/s²

A = Area

Y = Young's modulus = [tex]9.4\times 10^9\ N/m^2[/tex]

When we divide stress by young's modulus we get compressional strain

[tex]\frac{\Delta L}{L_0}=\frac{F}{A}\times \frac{1}{Y}\\\Rightarrow \frac{\Delta L}{L_0}=\frac{mg}{\pi(r_o^2-r_i^2)}\times \frac{1}{Y}\\\Rightarrow \frac{\Delta L}{L_0}=\frac{57\times 9.81}{\pi((1.07\times 10^{-2})^2-(3.7\times 10^{-3})^2)}\times \frac{1}{9.4\times 10^9}\\\Rightarrow \frac{\Delta L}{L_0}=0.00018784[/tex]

Compressional strain of the humerus is 0.00018784