Test: Elasticity - UPSC MCQ

Elasticity refers to the ability of a material to withstand distorting influences and return to its original size and shape once the external force is removed. Unlike plasticity, where deformation is retained, elastic materials have the capacity to bounce back. For example, rubber bands and springs exhibit elastic behavior, allowing them to stretch or compress under force and then return to their original form when the force is removed.

Longitudinal stress occurs when the stress is normal to the body's surface area and leads to a change in length of the material. This type of stress includes both tensile stress, which causes stretching, and compressive stress, which results in material compression. It's essential to understand these stress types to analyze how materials respond to external forces.

Volumetric strain, also known as volume strain, describes the change in volume relative to the initial volume caused by external deformation-producing forces. It is a measure of how much the volume of a material changes under stress, providing valuable information about its response to external forces.

The stress-strain curve provides insights into the mechanical properties of solids by illustrating the relationship between stress and strain for a material subjected to varying loads. This curve helps in understanding how a material deforms under stress and how it behaves within its elastic and plastic limits.

Young's modulus, also known as the modulus of elasticity, measures a material's ability to tolerate compression or elongation relative to its length. It quantifies the stress required to induce a unit of strain, providing crucial information about a material's mechanical behavior under stress.

In Hooke's Law, σ represents stress. Hooke's Law establishes a proportional relationship between stress and strain within a material's elastic limit, illustrating how stress affects the deformation of a material.

Plastic deformation occurs at the yield point on the stress-strain curve. Beyond this point, the material undergoes permanent changes in shape, indicating the onset of plasticity.

Steel typically exhibits linear-elastic behavior according to Hooke's Law. This means that within its elastic limit, the relationship between stress and strain is linear, making steel a material commonly used in engineering applications where predictable deformation is desired.

The unit of measurement for Young's modulus is the pascal (Pa). Young's modulus quantifies the stress required to induce a unit of strain in a material, and its SI unit is the pascal, which is equivalent to one newton per square meter (N/m²).

The ultimate stress point on the stress-strain curve indicates the maximum stress a material can withstand before failure occurs. Beyond this point, the material fractures or breaks, leading to structural failure.

Shear stress arises when the applied force is tangential or parallel to the body's surface, causing a shift or twist in the shape of the object. This type of stress is common in materials subjected to cutting, punching, or bending forces.

Elastic hysteresis represents the energy lost as heat during loading and unloading cycles of a material. It accounts for the difference between the strain energy required to achieve a particular stress and the elastic energy stored in the material.

Volume stress, also known as bulk stress, occurs when a deforming force acts in all dimensions, resulting in a change in the body's volume. This type of stress is important in understanding how materials respond to external pressures or forces.

The proportional limit on a stress-strain curve represents the point at which the curve becomes linear, indicating the range within which Hooke's Law applies. It's the point where stress and strain are directly proportional, and the material behaves elastically without undergoing permanent deformation.

Shearing strain occurs when the applied force alters the shape of the body, causing layers of the material to shift relative to each other. This type of strain is common in materials subjected to forces that induce twisting or sliding motions.