👉 A fluid, in the context of physics and engineering, is a substance that flows easily under applied stress or force, such as pressure or shear, without breaking apart into discrete particles. Unlike solids, which maintain their shape and volume, or gases, which expand to fill any container, fluids can change shape to conform to their container while retaining their chemical composition. Examples include liquids like water and oils, and gases such as air. The fluid behavior is governed by principles like viscosity, which describes a fluid's resistance to flow, and surface tension, which arises from cohesive forces between fluid molecules. Understanding fluid dynamics is crucial in various applications, from designing pipelines and engines to predicting weather patterns and ocean currents.
