|Table of Contents|
What Is Bulk modulus?
- Bulk modulus is defined as the proportion of volumetric stress related to the volumetric strain of specified material while the material deformation is within the  elastic limit.
- In simpler words, the bulk modulus is nothing but a numerical constant that is used to measure and describe the elastic properties of a solid or fluid when pressure is applied to all the surfaces.
- The bulk modulus of elasticity is one of the measures of the mechanical properties of solids.
- Other elastic modules include Young’s modulus and Shear modulus.
- In any case, the bulk elastic properties of a material are used to determine how much it will compress under a given amount of external pressure.
- Here, it is important to find and note the ratio of the change in pressure to the fractional volume compression.
- The value is denoted with a symbol of K, and it has the dimension of force per unit area.
- It is expressed in the units per square inch (psi) in the English system and newtons per square meter (N/m2) in the metric system.
in the units per square inch (psi) in the English system and newtons per square meter (N/m2) in the metric system.
Following is the table explaining other related concepts:
|Relation between Young’s Modulus and Bulk Modulus|
|Shear Modulus of Rigidity|
Bulk Modulus of Elasticity Formula
It is given by the ratio of pressure applied to the corresponding relative decrease in the volume of the material.
Mathematically, it is represented as follows:
B = ΔP /(ΔV/V)
B: Bulk modulus
ΔP: change of the pressure or force applied per unit area on the material
ΔV: change of the volume of the material due to the compression
V: Initial volume of the material in the units of in the English system and N/m2 in the metric system.
What is the bulk modulus of a body that experienced a change of pressure of 5*104N/m2 and its volume goes from 4 cm3 to 3.9 cm3?.
The bulk modulus is calculated using the formula,
B = ΔP /(ΔV/V)
B = (5*104 N/m2)/((4 cm3 – 3.9 cm3)/4 cm3) = 0.125 *104 N/m2
B = 1.25 *104 N/m2
- Bulk modulus measures how incompressible a solid is.
- Besides, the more the value of K for a material, the higher its nature is incompressible.
- For example, the value of K for steel is 1.6×1011N/m2, and the value of K for glass is 4×1010N/m2.
- Here, K for steel is more than three times the value of K for glass.
- This implies that glass is more compressible than steel.
- While in solids, Young’s modulus is commonly used, the value of K varies in gases, as they are extremely compressible. The concept of Bulk Modulus is also used in liquids. Temperatures of fluid and entrained air content are the two factors highly controlled by the bulk modulus.
Watch the video and understand solids’ elastic and plastic behaviour
Frequently Asked Questions – FAQs
What is elastic modulus?
What is permanent deformation?
What is temporary deformation?
What is strain?
Explore more about physics formulas and calculators with our expert faculty, here at BYJU’S.
Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!
Select the correct answer and click on the “Finish” button
Check your score and answers at the end of the quiz
Visit BYJU’S for all Physics related queries and study materials
Your result is as below