# The difference of bulk and young modulus

• saray1360
In summary, the difference between bulk modulus and young modulus lies in their respective definitions and applications. While bulk modulus measures the resistance to volume change under pressure, young modulus measures the resistance to length change under stress. They are approximately equal when Poisson's ratio is near 0.33.

#### saray1360

Hi everyone,

I want to know what the difference between bulk modulus and young modulus is? In some papers, it seems that they have compared the value of these two as if they are the same.

Could anyone help me with this regard?

Regards,
Sara

Youngs modulus refers to stretching and bulk modulus refers to compressing.

it is not the answer, sorry

Youngs modulus and bulk modulus are different..The former is tensile stress/tensile strain the latter is bulk stress/bulk strain.

Youngs modulus and bulk modulus are different..The former is tensile stress/tensile strain the latter is bulk stress/bulk strain.

The bulk modulus K is the amount of pressure required to obtain a certain change in volume per unit volume. The Young's modulus is $E=3(1-2\nu)K$ (*). For a rod (long, thin geometry), it is the amount of axial stress (compression or tension) required to obtain a certain change in axial length per unit length. They are approximately equal when $\nu$ is near 0.33, which is common for metals (but not for ceramics or elastomers).

(*) $\nu$ is Poisson's ratio, the ratio of the lateral contraction over the axial contraction for a rod under axial load.

EDIT: Removed unnecessary comment.

Last edited:

## What is the definition of bulk modulus?

The bulk modulus, also known as the volume modulus, is a measure of a material's resistance to uniform compression.

## What is the definition of young modulus?

The young modulus, also known as the tensile modulus, is a measure of a material's stiffness or resistance to deformation when under tension.

## How are bulk and young modulus different?

The main difference between bulk and young modulus is the type of force each measures. Bulk modulus measures the resistance to compression, while young modulus measures the resistance to tension.

## What are the units of measurement for bulk and young modulus?

Bulk modulus is typically measured in Pascals (Pa) or Gigapascals (GPa), while young modulus is measured in Pascals (Pa) or Megapascals (MPa).

## How are bulk and young modulus used in materials science?

Bulk and young modulus are important parameters used in materials science to characterize the mechanical properties of different materials. They are used to determine a material's ability to withstand compression or tension, which is important in engineering and design applications.

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