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What is temperature?. All substances are made of atoms and molecules All molecules are in constant, random motion There is energy associated with those motions (molecular kinetic energy) Temperature is a measure of the average molecular kinetic energy of a substance
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What is temperature? All substances are made of atoms and molecules All molecules are in constant, random motion There is energy associated with those motions (molecular kinetic energy) Temperature is a measure of the average molecular kinetic energy of a substance Temperature can be measured in terms of: Fahrenheit (degrees F) (used by U.S. and Liberia only) Pure water freezes at 32 deg F “Room temperature” 68 deg F Avg deep core body temp 98.6 deg F Boiling point of pure water at sea level 212 deg F Centigrade or Celsius (used by rest of the world) Pure water freezes at 0 deg C Pure wate at sea level boils at 100 deg C “Room temperature” 20 deg C Avg deep core body temp 37 deg C Kelvin (Kelvins) All molecular motion stops : 0 Kelvins A change of 1K equals a change of 1 deg C
What is pressure? • Collective force exerted by molecules of a substance in random motion, colliding against each unit of area of their surroundings (force per unit area) • Measured in terms of: • inches of mercury (in Hg) • millibars (mb) • atmospheres (atm) • Pounds per square inch (lbs/in2)