Fluids • A fluid is any form of matter (substance) that flows. Particle Theory • A review of the five major points of the particle theory of matter: • 1. All matter is made up of very small particles. • 2. All particles in a pure substance are the same. Different substances are made of different particles. • 3. There is space between the particles. • 4. The particles are always moving. As the particles gain energy, • they move faster. • 5. The particles in a substance are attracted to one another. Solids, Liquids and Gases • The strength of the attractive force depends on the type of particle. Solids Liquids Gases Shape Definite shape Indefinite shape Indefinite shape Volume Definite volume Definite volume Indefinite volume Particle arrangement Particles close Particles close Particles distant Particle movement Vibrate in place Free flowing Random movement Solids, Liquids and Gases Even though a solid does not appear to move, the particles are constantly vibrating in place. The particles in a liquid are in contact with each other, but they can slip and slide past one another, changing their position. This slipping and sliding means liquids take the shape of their container. Gas particles have very large spaces between them. from liquids and solids. Particles in a gas can move freely in all directions. This is why gases always spread out or diffuse in their container Fluids:Liquids and Gases • Since liquids and gases do not have a definite shape they are able to flow. Hence by definition, liquids and gases are fluids. • Some examples of fluids in everyday life: (i) compressed air in tires (ii) water (iii) syrup Other Fluid Examples Other examples include: • - food fluids (syrup, honey, molasses, water, or oil.) • - cleaning fluids (shampoo, liquid detergents, gels, abrasive creams like Vim™) • - bodily fluids (blood, mucus) • - industrial fluids (oils as lubricant, compressed air in tires)