# Why is Young's Modulus important?

Young’s modulus or the modulus of elasticity is a mechanical property that measures the tensile stiffness of a solid material. Young’s modulus is a numeric constant that is named after the physicist Thomas Young. It is a fundamental property of materials that is dependent on temperature and pressure. The Young’s modulus of elasticity measures the material’s ability to resist deformations in length under lengthwise compression or tension.

The Young’s modulus of a given material is the ratio of stress and strain. Mathematically, represented as follows:

$$\begin{array}{l}E=\frac{\sigma }{\epsilon }\end{array}$$

where E is the Young’s Modulus of the material given in N/m2, σ is the stress applied to the material and ϵ is the strain corresponding to applied stress in the material.

The SI unit for Young’s modulus is Pa, often the values are expressed in terms of gigapascals (GPa), megapascal (MPa) and

Diamond has the highest value of Young’s modulus. Flexible materials have low Young’s modulus and change its shape considerably. Concluding we can say that materials with high Young’s modulus indicate that they are inelastic and stiff while materials with low Young’s modulus elastic and can be easily deformed.

The Young’s modulus of some common materials are listed below:

• Steel – 200
• Glass – 65
• Wood – 13
• Plastic (Polystyrene) – 3
• Concrete – (15 – 40)

Young’s modulus is essential to predict the behaviour of materials when subjected to a force. For example, while choosing materials for beams used in the bridge to withstand a large load of the moving traffic, we need to choose materials with high Young’s modulus. The beams are generally made of concrete with sufficiently high modulus of elasticity. Similarly, a railway track is made of steel which has a high modulus of elasticity which allows it to bear the compression load applied by the train.

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