Doing work in boring a cannon immersed in water and

This preview shows page 2 - 5 out of 36 pages.

doing work in boring a cannon immersed in water and boiling the water, Thompson was able to demonstrate that the work of boring was converted into heat. Thompson’s image is shown in Fig. 5.1a. Thompson’s etching of the cannon used in his experiment is reproduced in Fig. 5.1b. a) b) Figure 5.1: a) Sir Benjamin Thompson (Count Rumford) (1753-1814) in a 1783 portrait by Thomas Gainsborough. American scientist whose cannon-boring experiments discredited the caloric theory. Image from Thompson , b) Image of cannon from B. Thompson (Count Rumford), 1798, “An inquiry concerning the source of the heat which is excited by friction,” Philosophical Transactions of the Royal Society of London , 88: 80-102. 1 B. Thompson (Count Rumford), 1798, “An inquiry concerning the source of the heat which is excited by friction,” Philosophical Transactions of the Royal Society of London , 88: 80-102. CC BY-NC-ND. 2011, J. M. Powers.
Image of page 2

Subscribe to view the full document.

5.1. REPRESENTATIONS OF THE FIRST LAW 103 In the 1840s there was considerable effort to relate mechanical and thermal energy and measure J , the so-called mechanical equivalent of heat. There is some controversy over who first quantified this value. By many accounts Julius Robert von Mayer achieved the first success in 1842, 2 though his exposition often lacked the mathematical and experimental support that many scientists demand. Mayer is pictured in Fig. 5.2. Contemporaneously, Figure 5.2: Julius Robert von Mayer (1814-1878). German physician and physi- cist who in 1842 said “Energy can be neither created nor destroyed.” Image from Robert von Mayer . and with more publicity, Joule spent considerable effort in carefully measuring J . 3 4 He estimated J = 4 . 41 J/cal , which has since been corrected to J = 4 . 1860 J cal . (5.2) We give a portrait of Joule in Fig. 5.3a. A nineteenth century etching of Joule’s device is given in Fig. 5.3b. A modern full-scale replica of Joule’s apparatus designed and constructed by Mr. Leon Hluchota and Prof. Patrick F. Dunn, based upon Joule’s original experimental display in the Science Museum, London, and in use in undergraduate laboratories at the University of Notre Dame, is shown in Fig. 5.3c. 2 J. R. Mayer, 1842, “Bemerkungen ¨uber die Kr¨afte der unbelebten Natur,” Annalen der Chemie und Pharmacie , 42: 233-240. 3 J. P. Joule, 1845, “On the existence of an equivalent relation between heat and the ordinary forms of mechanical power,” The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science , Ser. 3, 27: 205-207. 4 J. P. Joule, 1850, “On the mechanical equivalent of heat,” Philosophical Transactions of the Royal Society of London , 140: 61-82. CC BY-NC-ND. 2011, J. M. Powers.
Image of page 3
104 CHAPTER 5. THE FIRST LAW OF THERMODYNAMICS a) b) c) Figure 5.3: a) James Prescott Joule (1818-1889). English experimen- talist who demonstrated the mechanical equivalent of heat. Image from Prescott Joule , b) Sketch of Joule’s origi- nal apparatus, from Harper’s New Monthly Magazine , No. 231, August 1869, c) Operational
Image of page 4

Subscribe to view the full document.

Image of page 5
You've reached the end of this preview.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern