Mechanics of Materials — Quiz 2

Questions in this quiz (10)

1. A tensile force of 120 kN is applied on a 0.025 m diameter and 2.5 m long rod. After applying the load, the diameter of the rod decreases to 0.024975 m and the length increases to 2.512 m. The lateral (transverse) strain is most nearly:

   • 0.05%
   • 0.10%
   • 0.15%
   • 0.20%

2. A tensile force of 120 kN is applied on a 0.025 m diameter and 2.5 m long rod. After applying the load, the diameter of the rod decreases to 0.024975 m and the length increases to 2.512 m. The Poisson's ratio of this material is most nearly:

   • 0.15
   • 0.21
   • 0.25
   • 0.30

3. A tensile force of 180 kN is applied on a 0.025 m diameter and 2.5 m long rod. After applying the load, the length increases to 2.515 m. Assuming no permanent deformation occurs, the modulus of elasticity (GPa) is most nearly:

   • 61.1
   • 200
   • 210
   • 225

4. A steel rod is 0.025 m in diameter and 3 m in length. The modulus of elasticity of this material is 200 GPa. The change in length after applying a tensile force of 180 kN is most nearly:

   • 4.6 mm
   • 5.5 mm
   • 6.6 mm
   • 7.6 mm

5. A steel rod is 0.025 m in diameter and 3 m in length. The modulus of elasticity is 200 GPa and Poisson's ratio is 0.28. The change in diameter after applying a tensile force of 180 kN is most nearly:

   • 0.006 mm
   • 0.013 mm
   • 0.018 mm
   • 0.024 mm

6. In a tensile test, if the yield point is not distinct, the yield point is determined by plotting an offset line parallel to the initial stress-strain curve. The parallel line is plotted at strain of:

   • 0.001
   • 0.002
   • 0.003
   • 0.004

7. The correct relationship among modulus of elasticity E, Poisson's ratio ν, and shear rigidity G is most nearly:

   • $$G = \frac{E}{[2(1+ν)]}$$
   • $$G = \frac{E}{[2(1-ν)]}$$
   • $$G = \frac{2E}{(1+ν)}$$
   • $$G = \frac{E(1+ν)}{2}$$

8. A 6-m steel rod has a coefficient of thermal expansion of $$7×10^{-6}$$ per °F. If the temperature decreases by 60°F, the thermal strain is most nearly:

   • 0.00021
   • 0.00042
   • 0.00063
   • 0.00084

9. A 12 m steel rod has a coefficient of thermal expansion of $$5×10^{-6}$$ per °F. If the temperature of the body is decreased by 40°F, the thermal contraction (m) is most nearly:

   • 1.2 × 10⁻³
   • 2.4 × 10⁻³
   • 3.0 × 10⁻³
   • 4.8 × 10⁻³

10. A 12 m steel rod is snugly supported by two rigid supports at the ends. The coefficient of thermal expansion is $$5×10^{-6}$$ per °F and the elastic modulus is 200 GPa. If the temperature increases by 40°F, the thermal stress developed is most nearly:

    • 25 MPa
    • 40 MPa
    • 50 MPa
    • 60 MPa