MATTER, MASS, DENSITY, PRESSURE, TEMPERATUREWorking 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. H20)

• Molecular H2, O2, N2 are NOT compounds (molecules are of a single element

• CO2, H2O, CH4 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 = 14.59 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• 29.92 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