Question

What is difference between young moduls and bulk modules

Answer 1

Young's Modulus of Elasticity :-

It is defined as the ratio of normal stress to the longitudinal strain. That is, Young's Modulus

$Y=\frac{Normal\:stress}{Longitudinal\:stress}$

Normal Stress = $\frac{F}{A}$

Longitudinal Strain = $\frac{\Delta\:L}{L}$

$Y=\frac{FL}{A\Delta\:L}$

Bulk Modulus:-

If a body is uniformly compressed from all sides then it undergoes a decrease in volume.

If p is the uniform compression on the body and $\Delta\:V$ is the change in volume V of the body, then it has been obtained experimentally that $p\propto\frac{\Delta\:V}{V}$

$p=-B(\frac{\Delta\:V}{V})$

$B=-\frac{PV}{\Delta\:V}$

The constant of proportionality B is called Bulk Modulus.