Hydraulic & Pneumatic Systems Properties of Fluids

Properties of Fluids Fluid: A substance that flows and takes the shape of its container. They also cannot form any shapes themselves. i.e: Water and air are fluids, sand and sugar are not. The study of fluids is divided into two branches: Hydraulics: The science behind the mechanical properties of liquids. Pneumatics: The science behind the mechanical properties of gases.

Systems & Our Bodies Our bodies contain natural pneumatic & hydraulic systems: Hydraulic system: Circulatory system, blood is circulated throughout the body. Pneumatic system: Respiratory system, air is brought in and out of the lungs.

Kinetic Molecular Theory Before we look at specific fluid properties, we re-examine the kinetic molecular theory which states: All substances are made up of identical molecules. The particles are in constant motion. Solids move the slowest -> Gases move the fastest Particles have spaces in-between them. Solids have smallest space -> Gases have most space.

Solid Liquid Gas

Density Defined as the mass per unit volume. Given by: Eg.1: A substance has a mass of 150g and a density of 4.5 kg/m3, what volume does it occupy? Where D = density (kg / m3) m = mass (kg) V = volume (m3)

Compressibility The ability of a substance to be pressed closer together. Gases are more compressible than liquids. Why? Particle theory of matter states spaces between gases are larger than liquids. These spaces can be shrunk.