1 / 26

Temperature

Temperature. Physics 313 Professor Lee Carkner Lecture 2. Thermodynamics. Thermodynamics is the study of energy e.g. a cylinder of gas accelerated to high speed has an increased kinetic energy but the same temperature

carson
Download Presentation

Temperature

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Temperature Physics 313 Professor Lee Carkner Lecture 2

  2. Thermodynamics • Thermodynamics is the study of energy • e.g. a cylinder of gas accelerated to high speed has an increased kinetic energy but the same temperature • We will discuss the properties of a system and how they relate to internal energy, through both the macroscopic and microscopic points of view

  3. Specify a few basic bulk properties Classical Thermodynamics Specify states of individual units Statistical mechanics Macroscopic Microscopic

  4. Systems • Material separated from its surroundings by a boundary • Closed • e.g. gas in a piston • Open • e.g. an automobile radiator

  5. Processes • State • Process • Quasi - Static (Quasi-Equilibrium) Process • slow changes • Non-quasi static processes are discontinuous

  6. Equilibrium • Define two properties for a system • If the two properties remain constant the system is in equilibrium • A system is in equilibrium with itself if its properties are constant throughout the whole system

  7. System Boundaries • Adiabatic Wall • thermal insulator • Dithermal wall • thermal conductor

  8. Temperature Proxies • Changes in temperature cause changes in other system properties • Two consequences: • We measure T by measuring changes in other properties • If T is not constant, nothing else is • Often given at standard temperature (0 C) or room temperature (20 C)

  9. Thermal Expansion • The degree to which a linear distance varies with temperature is given by: • Change in one dimension (linear expansion) • Very small (~one part in a million per degree) in most cases • Note that a itself is temperature dependant

  10. Typical “toothed” bridge expansion joint

  11. “Rocker” support that allows deck expansion

  12. “Sleeved” railing expansion section

  13. The Brooklyn Bridge

  14. The Brooklyn Bridge • Built: • Designed: John A Roebling • Chief Engineer: Washington A. Roebling • Height: • Length: • World’s longest suspension bridge until 1903 • To learn more about the Brooklyn Bridge visit your local library: • The Great Bridge : The Epic Story of the Building of the Brooklyn Bridge by David McCullough

  15. Brooklyn Bridge cables

  16. Stringing the Cables

  17. Main Cable

  18. Thermal Equilibrium • Two systems separated by a dithermal wall that do not change properties • If the two systems are not in thermal equilibrium they will exchange heat until they are

  19. Zeroth Law • Three systems A, B and T • A and T -- • B and T -- • Then for A and B • Two systems in thermal equilibrium with a third are in thermal equilibrium with each other

  20. Isotherms • Plot pressure and volume • Curve is called an isotherm • Temperature determines thermal equilibrium

  21. Temperature • Take an object T and mark it so that changes in its properties can be measured • Calibrate the measurements so that your scale corresponds to universally accepted situations • e.g. mercury thermometer

  22. Temperature Scales • Gabriel Daniel Fahrenheit invented the mercury thermometer in 1714 • 32 F is freezing point of water, 212 is chosen for boiling point (32+180) • Anders Celsius introduced his scale in 1742 • William Thomson, Lord Kelvin, developed the absolute (Kelvin) scale from his analysis of ideal engines

  23. Temperatures • Universe (Planck time) ~ • Universe (today) ~ • Average star ~ • Average dust cloud ~ • Planet (Mercury) ~ • Planet (Neptune) ~ • Planet (habitable) ~

More Related