Chapter 9: Mechanical Properties of Solids

• Stress = Force/Area
• Strain = ∆L/L
• Young's modulus Y = Stress/Strain
• Y = FL/(A∆L)

Q1. A wire of length 2 m and area 1 mm² is stretched by 0.5 mm under load. Find Young's modulus if the load is 100 N.

Solution

Y = FL/(A∆L) = (100 × 2)/(1 × 10⁻⁶ × 0.5 × 10⁻₃)
= 200/(5 × 10⁻²) = 4 × 10² N/m²