Fließmaterial
Fließmaterial refers to any substance that can flow, meaning it deforms continuously under an applied shear stress. This broad category primarily encompasses liquids and gases, which are collectively known as fluids. The defining characteristic of fließmaterial is its ability to change shape without fracturing, conforming to the container it occupies. This property is directly related to the internal structure and intermolecular forces within the substance. In liquids, molecules are relatively close together but can move past one another, resulting in a fixed volume but a variable shape. Gases, on the other hand, have molecules that are widely spaced and move randomly, leading to both variable volume and variable shape. The study of fließmaterial is known as fluid mechanics, a branch of physics and engineering that investigates the behavior of fluids at rest (fluid statics) and in motion (fluid dynamics). Key properties studied include viscosity, density, and compressibility, which dictate how a specific fließmaterial will behave under various conditions. Examples of fließmaterial range from water and air to honey and even molten metals.