Young’s Modulus, also known as the elastic modulus or modulus of elasticity, is a measure of the stiffness of a material. It quantifies the ability of a material to deform elastically under an applied load. Young’s Modulus is named after the 18th-century scientist Thomas Young, who first introduced the concept.
Mathematically, Young’s Modulus (E) is defined as the ratio of stress (σ) to strain (ε) in a material undergoing elastic deformation. The relationship is expressed by Hooke’s Law, which states:
σ=E⋅ε
Where:
- σ is the stress (force per unit area),
- E is Young’s Modulus,
- ε is the strain (relative deformation or change in size).
In terms of units, Young’s Modulus is measured in pascals (Pa) or newtons per square meter (N/m²) since stress is force per unit area and strain is a dimensionless quantity.
Young’s Modulus represents the slope of the linear portion of the stress-strain curve in the elastic region of a material. It describes how much a material will deform under a given load and is a crucial parameter in engineering and materials science. Materials with higher Young’s Modulus values are stiffer and deform less under a given load, while materials with lower values are more flexible and deform more.
Daily Life Examples of Young’s Modulus
| Number | Material | Young’s Modulus (GPa) | Analogy |
|---|---|---|---|
| 1 | Rubber Bands | 0.01 – 0.1 | Stretch easily |
| 2 | Steel Springs | 200 – 210 | Resist bending, like springs in a mattress. |
| 3 | Aluminum Foil | 68 | Bendable but retains some rigidity |
| 4 | Wooden Pencils | 10 – 20 | Balanced flexibility |
| 5 | Concrete Structures | 25 – 40 | Rigid and resistant to deformation |
| 6 | Plastic Drinking Straws | 2 – 3 | Easily bendable |
| 7 | Nylon Ropes | 2 – 4 | Strong yet flexible |
| 8 | Glass Panes | 70 – 90 | Rigid and resistant to bending, like glass. |
| 9 | Human Hair | 0.002 – 0.02 | Easily stretched |
| 10 | Copper Wires | 100 – 400 | Maintains shape under tension |
Stiffness of a material vs. Young’s Modulus
The terms “stiffness of a material” and “Young’s Modulus” are related concepts, but they are not exactly the same. Stiffness is a general term that describes a material’s ability to resist deformation when subjected to an applied force. It is a property that can be characterised by various measures, and Young’s Modulus is one of them.
Young’s Modulus (E) is a specific material property that quantifies its stiffness in the elastic range.
| Stiffness of a Material | Young’s Modulus |
|---|---|
| Describes a material’s ability to resist deformation. | A specific measure of a material’s stiffness in the elastic range. |
| A general term indicating how much a material bends or deforms under an applied force. | Denoted by the symbol E. |
| Can be expressed in various ways, not limited to a specific numerical value. | Represents the ratio of stress to strain in the linear elastic region. |
| Provides a numerical value indicating how much a material deforms under a given load. | |
| Standardized and specific, often used in materials science and engineering. |
