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⚛️ Physics  ·  Mechanical Properties of Solids  ·  NEET & JEE

A rod (Y = 2×10<sup>11</sup> Pa, α = 1.2×10<sup>-5</sup> /K) is clamped rigidly between two walls and heated through 50 K. The thermal stress developed is:

Answer: 1.2×10 8 Pa.

  • A 0.6×10<sup>8</sup> Pa
  • B 1.2×10<sup>6</sup> Pa
  • C 2.4×10<sup>8</sup> Pa
  • D 1.2×10<sup>8</sup> Pa

Correct answer: D. 1.2×10<sup>8</sup> Pa

Explanation: Thermal stress = YαΔT = 2×10<sup>11</sup> × 1.2×10<sup>-5</sup> × 50 = 1.2×10<sup>8</sup> Pa.

Stress-Strain Curve for a Ductile Metal WireStrainStresselastic limityield pointUTS (max stress)fractureSlope of the straight (elastic) portion = Young's modulus Y; the curve beyond elastic limit shows permanent (plastic) deformation

A typical stress-strain curve: the initial straight line (Hooke's Law region, slope = Young's modulus) ends at the elastic limit; beyond the yield point, deformation becomes permanent, peaking at the ultimate tensile strength before the wire finally fractures.

Concept context

Stress, strain, Hookes law, and the elastic moduli that describe how solids deform and recover under load.

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