Fluid – Flowing Liquids and gases flow freely from place to place and assume the shape of any container into which they are put.

Liquids – have a definite volume, but no definite shape. Will change shape to fit its container, but will not expand to fill it completely.

Gases – have no definite volume or shape. Changes in both shape and volume to completely fill its container.

Atomic Theory of Matter – All matter is made up of indivisible particles called atoms, which combine into molecules. Made by John Dalton Basis for our understanding of fluids.

Kinetic Theory of Matter – Molecules of matter are in constant motion. Made by Daniel Bernoulli

Diffusion – The mixing of molecules of one fluid through another by random molecular motion.

Cohesion - When molecules of the same kind stick together.

Adhesion - When molecules of different kinds stick together.

Surface Tension – The tendency of a liquid to act as if it has a thick film on its surface.

Capillary Action– The phenomenon in which liquids in thin tubes rise above (or fall beneath) their own levels.

Effort (E) – The force we apply to the machine.

Specific Gravity– The number which compares an object’s density to the density of water. Specific Gravity = Density of object / Density of water

Hydrometer – A simple device for measuring the specific gravity of liquids.

If the specific gravity of lead is 35, how many times more dense is lead than water? 35

Pressure– The force exerted per unit of area. Pressure = Force / Area Usually given in pounds per square inch (psi)

Gravitational Pressure – A fluid’s weight causes it to exert more pressure at greater depths. Is applied equally in every direction.

If the pressure at the bottom of a 75 foot high tank of water is 30psi, what would be the pressure at the bottom of the same tank if it were filled with Hydrogen? The specific gravity of liquid Hydrogen is x 30 = 2.1psi