Two tapering bars of the same material are subjected to a tensile loa...
To determine the ratio of elongation of bar A to bar B, let's consider the properties of the bars and analyze the behavior under tensile load.
Given:
- Both bars have the same length.
- Bar A has a larger diameter at its larger end (D) and a smaller diameter at its smaller end (D/2).
- Bar B has a larger diameter at its larger end (D) and a smaller diameter at its smaller end (D/3).
Analysis:
1. Cross-sectional Area:
- The cross-sectional area of bar A varies linearly from D²/4 to (D/2)²/4.
- The cross-sectional area of bar B varies linearly from D²/4 to (D/3)²/4.
2. Stress:
- The stress experienced by both bars is given by the formula: Stress = Load / Area.
- As the load is the same for both bars (P), the stress will be inversely proportional to the cross-sectional area.
3. Strain:
- Strain is defined as the ratio of the change in length to the original length.
- The elongation of a bar is directly proportional to the strain, given by the formula: Strain = Stress / Young's Modulus.
4. Young's Modulus:
- Young's Modulus is a material property that describes its stiffness or resistance to deformation under load.
- Since both bars are made of the same material, their Young's Modulus values are equal.
Calculation:
1. Elongation of Bar A:
- Since the stress is inversely proportional to the cross-sectional area, the strain in bar A will be inversely proportional to the cross-sectional area.
- The strain in bar A will be (D/2)²/4 / D²/4 = (D/2)² / D² = 1/4.
- Therefore, the elongation of bar A will be 1/4 times the elongation of bar B.
2. Elongation of Bar B:
- The strain in bar B will be (D/3)²/4 / D²/4 = (D/3)² / D² = 1/9.
Ratio of Elongation:
- Elongation of bar A : Elongation of bar B = 1/4 : 1/9
- Simplifying the ratio, we get 9/4 : 1
- Therefore, the ratio of elongation of bar A to bar B is 9:4, which is equivalent to 2:3 (approximately).
Therefore, the correct answer is option 'B' - 2:3.
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