Question

Which of the following statements are correct?
(1) Young's modulus, bulk modulus and shear modulus have the units of pressure
(2) Young's modulus describes the length elasticity of a material
(3) The value of Young's modulus depends on the dimensions of the body
(4) Modulus of elasticity is the smallest value of stress required to produce a permanent distortion in a body

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (B)

$Y=\frac{\text{ longitudinal stress }}{\text{ longitudinal strain }}$
$B=\frac{\text{ normal stress }}{\text{ volume strain }}$
$\eta =\frac{\text{ shearing stress }}{\text{ shearing strain }}$
As strain is dimensionless, hence $Y,B$ and $\eta$ possess the units of pressure.
$Y$ depends on the material of :he body only. It is related with length elasticity of material.