The Young Modulus

• What does the Young modulus measure?

  Ability of a material to withstand length changes

  
• Why is the Young modulus important for engineers?

  It ensures materials can withstand sufficient forces

  
• How is the Young Modulus defined mathematically?

  Ratio of tensile stress to tensile strain

  
• What is the formula for tensile stress?

  $\text{Stress} =$$\frac{F}{A}$
• What does the variable F represent in the Young Modulus formula?

  Force in newtons (N)

  
• What does the variable A represent in the Young Modulus formula?

  Cross-sectional area in square meters (m²)

  
• What does the variable ΔL represent in the Young Modulus formula?

  Extension in meters (m)

  
• What are the units of the Young Modulus?

  Pascals (Pa)
• What is typically the order of the Young Modulus for materials?

  Very large numbers, in the order of GPa

  
• What is the relationship between Young Modulus and stress-strain graphs?

  • Young Modulus is the gradient of a linear stress-strain graph
  • It applies in the region where Hooke's Law is obeyed
  • Area under the graph equals energy stored per unit volume

  
• What phrase can help remember the order of stress and strain in the Young modulus equation?

  “When you’re stressed, you show the strain”

  
• How do you calculate the Young Modulus from a stress-strain graph?

  1. Determine stress and strain at the linear region's end
  2. Calculate the gradient of the graph in this region

  
• What is the Young Modulus of a copper wire if the gradient is $112.5 \times 10^6$ and strain is $0.9 \times 10^{-3}$?


  $1.25 \times 10^{11} \text{ Pa}$