Question

What are fluids? Give two examples.

Answer 1

To answer this question, we first need to understand what chemical substances are. A chemical substance is a type of stuff with a predictable chemical makeup and behavior. Physical separation procedures, i.e., breaking chemical bonds, cannot separate a chemical substance into its constituent elements, according to some references.

Complete answer:
Fluid - A fluid is a liquid, gas, or other material that deforms (flows) continuously as a result of an applied shear stress or external force. They have a zero-shear modulus, or, to put it another way, they are substances that cannot withstand any shear stress.
Liquids, on the other hand, generate a free surface (one that is not created by the container), but gases do not.
Although the term "fluid" refers to both the liquid and gas phases, it has different meanings in different fields. The definition of "solid" varies as well, as some substances can be both "fluid" and "solid" depending on the field. When a sudden force is applied to viscoelastic fluids like Silly Putty, they appear to behave like solids.
Two examples - Fluids are substances that have the ability to flow. Gases (oxygen, hydrogen), for example, and liquids (water, petrol, sulphuric acid).
So, we conclude that, A fluid is a liquid, gas, or other material that deforms continuously when subjected to shear stress, or an external force. They have a zero-shear modulus, or, to put it another way, they are substances that cannot withstand any shear stress. Gases do not create a free surface, but liquids do.

Note :
Fluids can be classified as one of the following based on the relationship between shear stress and the rate of strain and its derivatives: Newtonian fluids are those in which stress is proportional to strain rate. Higher powers and derivatives of non-Newtonian fluids, when stress is not proportional to rate of strain. Newtonian fluids, often known as viscous fluids, obey Newton's law of viscosity.