Asked in FBISE Physics 2022 — Paper 2 2022Moderate

if both the length and radius of the rod are doubled, then modulus of elasticity will:

Correct answer: C. Remains the same

  • A. inerease
  • B. Deerease
  • C. Remains the same
  • D. Be doubled

Explanation

When the length ( L ) and radius ( r ) of a rod are doubled, the new length and radius are ( 2L ) and ( 2r ) respectively. The modulus of elasticity ( E ) is defined as the ratio of stress to strain, and is given by: E= Stress/StrainBy solving it, we find that modulus of elasticity become half.But it is an intrinsic property of a material, meaning it does not change with the dimensions of the material. Therefore, if both the length and radius of the rod are doubled, the modulus of elasticity will remain unchanged.

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About Young's Modulus and Stress-Strain

Stress and strain describe how a solid deforms under an applied force, while Young's modulus is the ratio of tensile stress to tensile strain within the elastic limit. The topic includes elastic and plastic behaviour, Hooke's law, the stress strain graph and the difference between stiffness, strength and breaking stress.

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