Numford

Properties of matterClass 11, Mechanical Properties of Solids

Dimensional formula of Shear modulus

[M L-1 T-2]

SymbolG SI unitpascal (Pa)

Shearing stress divided by shearing strain, also called the modulus of rigidity.

Derivation

How to get the dimensional formula of shear modulus

  1. Start from the definition: shear modulus = stress / strain.
  2. velocity = length / time, so velocity is [L] / [T] = [L T-1].
  3. acceleration = velocity / time, so acceleration is [L T-1] / [T] = [L T-2].
  4. force = mass × acceleration, so force is [M] × [L T-2] = [M L T-2].
  5. area = length × length, so area is [L] × [L] = [L2].
  6. stress = force / area, so stress is [M L T-2] / [L2] = [M L-1 T-2].
  7. strain = length / length, so strain is [L] / [L] = [M0 L0 T0].
  8. Put in the dimension of each part: [M L-1 T-2] / [M0 L0 T0].
  9. Add the powers of each base quantity: [M L-1 T-2].
Same dimensions

Quantities with the dimensions [M L⁻¹ T⁻²]

Equal dimensions do not make them the same quantity. Compare shear modulus with the others in the full grid.

Practice

Three questions on shear modulus

1Which of these has the same dimensions as shear modulus?

2What is the SI unit of shear modulus?

3Which one has different dimensions from the others?

Questions

Shear modulus: quick answers

What is the dimensional formula of shear modulus?

The dimensional formula of shear modulus is [M L⁻¹ T⁻²]. It comes from shear modulus = stress / strain.

What is the SI unit of shear modulus?

The SI unit of shear modulus is the pascal (Pa).

Which quantities have the same dimensions as shear modulus?

Shear modulus shares [M L⁻¹ T⁻²] with energy density, pressure, stress, strain energy density, Young's modulus, bulk modulus. Equal dimensions do not make them the same quantity.

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