Math Problem Statement

In an experiment 400kg mass is Suspended at one end of the wire of length 3m and area of cross-section 20.2 cm2 . If the increase in length is 0.4cm, find stress, strain and young’smodulus.

Solution

To solve this problem, we'll calculate the stress, strain, and Young's modulus using the given dataTo solve this problem, we'll calculate the stress, strain, and Young's modulus using the given

1. Stress (σ\sigma):

Stress is defined as the force per unit area. The force in this context is the weight of the mass, which is given by F=mgF = mg, where:

  • m=400kgm = 400 \, \text{kg} (mass)
  • g=9.8m/s2g = 9.8 \, \text{m/s}^2 (acceleration due to gravity)

The cross-sectional area AA of the wire is given as 20.2cm220.2 \, \text{cm}^2. We need to convert this to m2\text{m}^2.

Steps:

  1. Calculate the force: F=400kg×9.8m/s2=3920NF = 400 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 3920 \, \text{N}

  2. Convert the area to m2\text{m}^2: A=20.2cm2=20.2×104m2=0.00202m2A = 20.2 \, \text{cm}^2 = 20.2 \times 10^{-4} \, \text{m}^2 = 0.00202 \, \text{m}^2

  3. Calculate the stress: σ=FA=3920N0.00202m21.94×106N/m2\sigma = \frac{F}{A} = \frac{3920 \, \text{N}}{0.00202 \, \text{m}^2} \approx 1.94 \times 10^6 \, \text{N/m}^2

2. Strain (ϵ\epsilon):

Strain is defined as the ratio of the change in length to the original length.

Given:

  • Original length L=3mL = 3 \, \text{m}
  • Increase in length ΔL=0.4cm=0.004m\Delta L = 0.4 \, \text{cm} = 0.004 \, \text{m}

Calculate the strain:

ϵ=ΔLL=0.004m3m1.33×103\epsilon = \frac{\Delta L}{L} = \frac{0.004 \, \text{m}}{3 \, \text{m}} \approx 1.33 \times 10^{-3}

3. Young's Modulus (EE):

Young's modulus is defined as the ratio of stress to strain.

Calculate Young's modulus:

E=σϵ=1.94×106N/m21.33×1031.46×109N/m2E = \frac{\sigma}{\epsilon} = \frac{1.94 \times 10^6 \, \text{N/m}^2}{1.33 \times 10^{-3}} \approx 1.46 \times 10^9 \, \text{N/m}^2

Final Answers:

  • Stress: σ1.94×106N/m2\sigma \approx 1.94 \times 10^6 \, \text{N/m}^2
  • Strain: ϵ1.33×103\epsilon \approx 1.33 \times 10^{-3}
  • Young's Modulus: E1.46×109N/m2E \approx 1.46 \times 10^9 \, \text{N/m}^2

Would you like further details on any of these calculations, or do you have any questions?

Relative Questions:

  1. How would the stress change if the mass were doubled?
  2. What would be the effect on Young's modulus if the wire material were different?
  3. How does the length of the wire affect the strain?
  4. Can stress and strain be directly measured in this experiment?
  5. What assumptions are made in this calculation of Young's modulus?

Tip:

Young's modulus is a material property, so it will remain constant for a given material regardless of the dimensions of the wire.

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Math Problem Analysis

Mathematical Concepts

Mechanics
Material Science

Formulas

Stress formula
Strain formula
Young's modulus formula

Theorems

Hooke's Law

Suitable Grade Level

Undergraduate level