MATTER, MASS, DENSITY, PRESSURE, TEMPERATURE Working toward basic Thermodynamics and Fluid Theory

Matter Defined: Anything that occupies space and has a mass Substances are composed of small particles called atoms.

Molecules Atoms combine to form more complex structures we call molecule In general – Electrically neutral group of two or more atoms held together Covalent bonds Different from Ions! Compounds versus molecules All compounds are molecules – not all molecules are compounds Compounds consist of 2 different elements (eg. H 2 0) Molecular H 2, O 2, N 2 are NOT compounds (molecules are of a single element CO 2, H 2 O, CH 4 are compounds (2 different types of elements

Mass The ‘amount of substance or matter’ A natural unit for mass is the mass of a proton or neutron AMU – atomic mass unit 1 slug = kg = 8.79 x10 27 amu 1 kg = 6.02 x 10 26

Density Mass of a sample of the material divided by the volume of the same sample

Specific Gravity Density comparison to water How dense is substance with respect to water

Pressure Defined as the force divided by the area on which it acts

Atmospheric Pressure We live under a ‘blanket of air’ Density of air decreases with altitude Sea Level: 14.7 psi in. Hg

Absolute Pressure and Gage Pressure ATM + Gage pressure = absolute pressure

Temperature Hot vs Cold Kinetic Energy of molecules Expansion of objects when heated Use of thermometers

K = C +273 R = F + 460