A circular bar 20 mm in diameter and 200 mm long is subjected to a fo...
E = 80 GPa = 80 × 10
3 MPa = 80 × 10
3 N/mm
2Stress = Load/Area
Strain = Stress/E
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A circular bar 20 mm in diameter and 200 mm long is subjected to a fo...
E = 80 GPa = 80 × 10
3 MPa = 80 × 10
3 N/mm
2Stress = Load/Area
Strain = Stress/E
A circular bar 20 mm in diameter and 200 mm long is subjected to a fo...
Given data:
Diameter of bar, d = 20 mm
Length of bar, L = 200 mm
Force applied, F = 20 kN = 20,000 N
Young's modulus, E = 80 GPa = 80 × 10^9 N/m^2
We know that the strain in a material is defined as the ratio of the change in length to the original length. In this case, the bar is subjected to an axial force, which will cause it to elongate. The strain can be calculated using the formula:
Strain = ΔL / L
where ΔL is the change in length and L is the original length.
To find ΔL, we can use the formula for axial stress:
Stress = F / A
where A is the cross-sectional area of the bar. For a circular bar, the area is given by:
A = πd^2 / 4
Substituting the values, we get:
A = π(20 mm)^2 / 4 = 314.16 mm^2
Now, the stress can be calculated as:
Stress = F / A = 20,000 N / 314.16 mm^2 = 63.66 N/mm^2
Using the formula for axial strain:
Strain = Stress / E
Substituting the values, we get:
Strain = 63.66 N/mm^2 / (80 × 10^9 N/m^2) = 7.9575 × 10^-4
Therefore, the strain in the bar is 7.9 × 10^-4.
Hence, option B is the correct answer.