# Unit 4 Section A Vocabulary Flashcard

 troposphere
 the layer of the atmosphere closest to Earth’s surface where most clouds and weather are located
 pressure
 equals force applied per unit area; in SI, pressure is expressed in pascals (Pa)
 International System of Units (SI)
 the modernized metric system
 base unit
 an SI unit that expresses a fundamental physical quantity (such as temperature, length, or mass)
 derived unit
 an SI unit formed by mathematically combining two or more base units
 newton (N)
 the SI unit of force that is roughly equal to the force exerted by a mass of 100 g at Earth’s surface
 force
 a push or pull exerted on an object; expressed by the newton (N), an SI unit
 meter
 the SI base unit of length
 pascal (Pa)
 the SI pressure unit; equal to one newton of force applied per square meter, 1 Pa = 1 N/m2
 kinetic molecular theory (KMT)
 observed gas behavior and gas laws explained by rapidly moving particles (gas molecules) that are relatively far apart and change direction only through collisions with each other or the container walls
 Boyle’s Law
 the pressure and volume of a gas sample at constant temperature are inversely proportional; PV = k
 kelvin temperature scale
 the absolute temperature scale, where zero kelvins (0 K) represents the theoretical lowest possible temperature; 0 degrees C = 273 K
 absolute zero
 the lowest temperature theoretically obtainable, which is 0K (zero kelvins), or -273 degrees C
 Charles’ law
 the volume of a gas sample at constant pressure is directly proportional to its kelvin temperature; V = kT