Shear Stress

Definition

Shear stress is the component of stress coplanar with a material cross-section. It is the stress which acts tangentially to the face of the section. Shear stress is an important concept in the study of elasticity, fluid mechanics, and the motion of objects in viscous fluids.

5 Must Know Facts For Your Next Test

1. Shear stress is responsible for the deformation of solid materials under load, leading to changes in shape without changes in volume.
2. In fluid mechanics, shear stress is the force per unit area that a fluid exerts on an object moving through it or on the boundaries containing the fluid.
3. Shear stress is a key factor in determining the onset of turbulence in fluid flow, as it can cause the fluid to separate from a surface and become unstable.
4. The motion of an object through a viscous fluid is influenced by the shear stress acting on the object's surface, which can create drag forces.
5. Poiseuille's law, which describes the flow of fluids through narrow tubes, is derived from the relationship between shear stress and the velocity gradient in the fluid.

Review Questions

• Explain how shear stress is related to the concept of elasticity and the deformation of solid materials.
  • Shear stress is a key component of the study of elasticity, as it is responsible for the deformation of solid materials under load. When a solid material is subjected to a shear stress, it experiences a change in shape without a change in volume. This deformation is described by the material's shear strain, which is the ratio of the change in shape to the original dimensions. The relationship between shear stress and shear strain is governed by the material's shear modulus, a measure of its resistance to deformation under shear loading.
• Describe the role of shear stress in the context of fluid mechanics, specifically in relation to the onset of turbulence and the motion of objects in viscous fluids.
  • In fluid mechanics, shear stress is a crucial factor in determining the behavior of fluids. Shear stress is responsible for the internal friction within a fluid, which can lead to the onset of turbulence. As the velocity gradient in a fluid increases, the shear stress also increases, and at a certain critical value, the flow can become unstable and transition from laminar to turbulent. Additionally, the motion of an object through a viscous fluid is influenced by the shear stress acting on the object's surface, which can create drag forces that impede the object's movement. The relationship between shear stress and the velocity gradient, as described by Poiseuille's law, is fundamental to understanding the flow of fluids through narrow tubes or channels.
• Analyze how the concept of shear stress is interconnected across the topics of elasticity, fluid mechanics, and the motion of objects in viscous fluids, and explain how a deep understanding of shear stress can provide insights into these related areas of physics.
  • Shear stress is a unifying concept that spans multiple topics in physics, including elasticity, fluid mechanics, and the motion of objects in viscous fluids. In the context of elasticity, shear stress is responsible for the deformation of solid materials, leading to changes in shape without changes in volume. This understanding of how shear stress affects the behavior of solids is crucial for designing structures and predicting their response to various loading conditions. In fluid mechanics, shear stress is a key factor in determining the onset of turbulence, as well as the flow of fluids through narrow channels, as described by Poiseuille's law. Furthermore, the motion of objects through viscous fluids is influenced by the shear stress acting on the object's surface, which creates drag forces that impede the object's movement. By deeply understanding the concept of shear stress and its interconnections across these related topics, students can gain a more comprehensive and integrated understanding of the fundamental principles of physics, which can provide valuable insights and enable them to solve complex problems in these areas.

Related terms

Stress: Stress is the force per unit area on a surface within a material. It can be normal (perpendicular to the surface) or shear (tangential to the surface).

Strain: Strain is the deformation of a material due to the application of a stress. It is the change in length per unit length of the material.

Viscosity: Viscosity is a measure of the resistance of a fluid to flow. It describes the internal friction within a fluid.