A cylindrical rod of steel (E = 207 GPa, 30 × 10 6 psi) having a yield strength of 310 MPa (45,000 psi) is to be subjected to a load of 11,100 N (2500 lb f ). If the length of the rod is 500 mm (20.0 in.), what must be the diameter to allow an elongation of 0.38 mm (0.015 in.)?

Respuesta :

Answer:

Diameter of the cylinder will be [tex]d=2.998\times 10^4m[/tex]

Explanation:

We have given young's modulus of steel [tex]E=207GPa=207\times 10^9Pa[/tex]  

Change in length [tex]\Delta l=0.38mm[/tex]

Length of rod [tex]l=500mm[/tex]

Load F = 11100 KN

Strain is given by [tex]strain=\frac{\Delta l}{l}=\frac{0.38}{500}=7.6\times 10^{-4}[/tex]

We know that young's modulus [tex]E=\frac{stress}{strain}[/tex]

So [tex]207\times 10^9=\frac{stress}{7.6\times 10^{-4}}[/tex]

[tex]stress=1573.2\times 10^{-5}N/m^2[/tex]

We know that stress [tex]=\frac{force}{artea }[/tex]

So [tex]1573.2\times 10^{-5}=\frac{11100\times 1000}{area}[/tex]

[tex]area=7.055\times 10^{8}m^2[/tex]

So [tex]\frac{\pi }{4}d^2=7.055\times 10^{8}[/tex]

[tex]d=2.998\times 10^4m[/tex]