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History 181B: Modern Physics

Class 3 (1/27/03)
New mechanical principles


 
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Outline The post-Newtonian programs
    Laplacian physics
    Rational mechanics
    What is at stake?

The nature of heat
    Motion, subtle fluid — or what?
    Towards heat as motion
    Joule's measurement
    Joule's background

Work, force, and energy
    Mechanical interests
    Conservation of energy and interconvertibility of forces
    Simultaneous discovery
    Mathematical formulation

Names and terms
Primary Secondary
Pierre Simon de Laplace (1749-1827)
subtle/imponderable fluids
action at a distance
caloric
Joseph Fourier (1768-1830), Analytical Theory of Heat (1822)
Benjamin Thompson, Count Rumford (1753-1814)
James Joule (1818-1889)
mechanical equivalent of heat
Michael Faraday (1791-1867)
energy
Naturphilosophie
Robert Mayer (1814-1878)
Hermann von Helmholtz (1821-1894)
 Joseph-Louis Lagrange (1736-1813), Analytical Mechanics (1788)
William Rowan Hamilton (1805-1865)
diffusion, Fourier series
vis viva, living force
Assignment James Prescott Joule, "On the Mechanical Equivalent of Heat" (1849), in The Scientific Papers of James Prescott Joule (London: Dawsons of Pall Mall, 1887), 298-328.

    Read pp. 298-306, skim the middle, read pp. 327-328 (beginning "The following table . . .").
    What is the point of the first 5 pages? (Why is Joule telling us this history?)
    Describe the essence of the experiment he was performing.
    What did Joule mean by "the mechanical equivalent of heat"? Why did he go to such efforts to ascertain it?
    What would your high-school science teacher think of Joule's lab write-up?
    Extra: What do you think is the point of the starred footnote on p. 328?

Copyright © Cathryn Carson 2003