Hooke's Law - Stress And Strain

Hooke’s Law Graph

The figure below shows the stress-strain curve for low carbon steel.

From the origin till the proportional limit nearing yield strength, the straight line implies that the material follows Hooke’s law. Beyond the elastic limit between proportional limit and yield strength, the material loses its elasticity and exhibits plasticity. The area under the curve from origin to the proportional limit falls under the elastic range. The area under the curve from a proportional limit to the rupture/fracture point falls under the plastic range.

The material’s ultimate strength is defined based on the maximum ordinate value given by the stress-strain curve (from origin to rupture). The value provides the rupture with strength at a point of rupture.

The video explains to you the general stress-strain graph of an elastic material experiencing tensile load and what are various stages in it. Within the elastic limit it follows Hooke’s law. As we keep on increasing the load, other stages and points like proportionality limit, yield point, fracture point, ultimate tensile strength are achieved, and they have been well explained in this video.

Hooke’s Law Applications

Following are some of the applications of Hooke’s Law:

• It is used as a fundamental principle behind the manometer, spring scale, the balance wheel of the clock.
• Hooke’s law sets the foundation for seismology, acoustics and molecular mechanics.

Hooke’s Law Disadvantages

Following are some of the disadvantages of Hooke’s Law:

• Hooke’s law ceases to apply past the elastic limit of a material.
• Hooke’s law is accurate only for solid bodies if the forces and deformations are small.
• Hooke’s law isn’t a universal principle and only applies to the materials as long as they aren’t stretched way past their capacity.

Frequently Asked Questions – FAQs

Q1

Does Hooke’s Law apply to all materials?

Hooke’s spring law applies to any elastic object of arbitrary complexity, as long as a single number can express the deformation and the stress.

Q2

Is Hooke’s Law linear?

Hooke’s Law is linear. Hooke’s law states that the restoring force is proportional to the displacement.

Q3

When does Hooke’s Law fail?

Hooke’s law applies to a perfectly elastic material and does not apply beyond the elastic limit of any material.

Q4

When is Hooke’s Law negative?

In Hooke’s law, the negative sign on the spring’s force means that the force exerted by the spring opposes the spring’s displacement.

Q5

Why do we need Hooke’s Law?

Hooke’s Law is essential because it helps us understand how a stretchy object will behave when stretched or compacted.

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