Test: Mechanical Properties of Solids - Hooke’s law & Stress-strain curve (29 July) - JEE MCQ

The point A refers to the point till which hooke’s law can be followed, i.e: stress ∝ strain. It is also called the proportional limit. The point B refers to the point upto which if stress is applied the metal, on removal of stress, will regain its natural length. It is called yield point or elastic limit. The point C refers to the maximum tensile strength. And point D refers to the point where the material breaks or fractures.

Breaking stress refers to the stress at which the material fractures. Ultimate stress is the maximum stress a material can handle before breaking. The material doesn’t fracture at this stress. Yield stress refers to the stress after which plastic deformation begins.

Ductile materials are those which can be drawn into wires as they deform by a significant amount between elastic limit and fracture point. The stress-strain curve of a ductile material looks like:

Brittle materials break soon after elastic limit. They show no significant plastic deformation and hence can’t be used for making wires. Their stress-strain curve looks like:

 Area under the stress-strain curves represents toughness. Total deformation is given by the net strain multiplied by original length. Modulus of elasticity is the ratio of stress to strain under elastic limit.

The Young's modulus of elasticity for the material of the wire is 10⁶ Pa.