Physics · Ch 8 — Heat and Thermodynamics
Introduction to Thermodynamic Systems
Introduction to Thermodynamic Systems
Thermodynamics is the branch of physics describing the laws governing the interconversion of work and heat, built up over three centuries of experimental work by Boyle, Charles, Bernoulli, Joule, Clausius, Kelvin, Carnot and Helmholtz -- and it governs everything from engines to the functioning of the human body. A thermodynamic system is any finite part of the universe chosen for study, described by macroscopic parameters pressure , volume and temperature ; everything outside it is the surroundings, and the two are separated by a boundary (Figure 8.15). Systems fall into three types (Figure 8.16): an open system exchanges both matter and energy with its surroundings (e.g. a bucket of water open to the atmosphere); a closed system exchanges only energy, not matter (e.g. air molecules sealed in a r …
What this figure shows. A simple schematic showing an irregular closed boundary (drawn as a wavy enclosed outline) labelled 'System' on the inside and 'Surroundings' on the outside, with the boundary itself explicitly labelled. The figure establishes the basic vocabulary used throughout the rest of the unit: any finite part of the universe chosen for study is the 'system', everything else is the 'surroundings', and the imaginary or real dividing line between them is the 'boundary' across which h …
What this figure shows. Three side-by-side schematic boxes labelled Open, Closed and Isolated. The 'Open' box shows arrows for both matter and energy crossing its boundary in both directions, representing a system that can exchange both matter and energy with its environment. The 'Closed' box shows only an energy arrow crossing its boundary (no matter arrow), representing a system that exchanges energy but not matter. The 'Isolated' box shows no arrows crossing its boundary at all, representing a system that exchanges neither energy nor matter with its surroundings. The textbook pairs this with everyday examples: a bucket of water in the open atmosphere (open), air molecules in a sealed room (closed, appr …