Stress

Definition

Stress is the internal force per unit area within materials that arises from externally applied forces, temperature changes, or other factors. It is usually measured in Pascals (Pa) and calculated as $ \sigma = \frac{F}{A} $ where $ F $ is the force applied and $ A $ is the cross-sectional area.

5 Must Know Facts For Your Next Test

1. Stress can be categorized into three main types: tensile stress, compressive stress, and shear stress.
2. The SI unit of stress is the Pascal (Pa), which is equivalent to one Newton per square meter (N/m²).
3. Hooke's Law states that for small deformations, stress is directly proportional to strain: $\sigma = E \epsilon$, where $E$ is Young's modulus.
4. When a material surpasses its elastic limit, it will undergo plastic deformation and may eventually fracture.
5. Normal stress acts perpendicular to the surface while shear stress acts parallel to the surface.

Review Questions

• What are the three main types of stress?
• How do you calculate stress using force and cross-sectional area?
• Explain Hooke's Law in terms of stress and strain.

Related terms

Strain: Strain is the measure of deformation representing the displacement between particles in the material body relative to a reference length. It is dimensionless.

Young's Modulus: Young’s Modulus, denoted as E, measures the stiffness of a solid material. It is defined as the ratio of tensile stress to tensile strain.

Elastic Limit: The elastic limit is the maximum amount of stress that a material can withstand without undergoing permanent deformation.